Liquid-crystalline medium and liquid-crystal display comprising the same

ABSTRACT

The invention relates to a liquid-crystalline medium, having particular dielectric properties, in that it has:
         either a dielectric constant perpendicular to the director (ε ⊥ ) in the range of 2 or more to less 8 or less and at the same time a ratio of the dielectric constant perpendicular to the director (ε ⊥ ) to the dielectric anisotropy (Δε), i.e. (ε ⊥ /Δε) of 1.0 or more or   or a dielectric constant perpendicular to the director (ε ⊥ ) of 8 or more and a dielectric anisotropy (Δε) of 26 or less and
 
preferably comprises one or more compounds having a high dielectric constant perpendicular to the director (ε ⊥ ) and a high average dielectric constant (ε av. ). These compounds are suitable for use in an electro-optical display, particularly in an active-matrix display based on the IPS or FFS effect.

The present invention relates to novel liquid crystalline media, inparticular for use in liquid-crystal displays, and to theseliquid-crystal displays, particularly to liquid-crystal displays whichuse the IPS (in-plane switching) or, preferably, the FFS (fringe fieldswitching) effect using dielectrically positive liquid crystals. Thelast one is also called SG-FFS (super grip FFS) effect occasionally. Forthis effect dielectrically positive liquid crystals are used, whichcomprise one or more compounds having at the same time a high dielectricconstant parallel to the molecular director and perpendicular to themolecular director, leading to a large average dielectric constant and ahigh dielectric ratio and, preferably, to a relatively small dielectricanisotropy at the same time. The liquid crystalline media optionallyadditionally comprise dielectrically negative, dielectrically neutralcompounds or both. The liquid crystalline media are used in ahomogeneous (i.e. planar) initial alignment. The liquid-crystal mediaaccording to the invention have a positive dielectric anisotropy andcomprise compounds having at the same time large dielectric constantsparallel and perpendicular to the molecular director.

The media are distinguished by a particularly high transmission andreduced response time in respective displays, which is brought about bytheir unique combination of physical properties, especially by theirdielectric properties and in particular by their high ratio of(ε_(⊥)/ε_(av.)) respectively of the high values of their dielectricratio (ε_(⊥)/Δε). This also leads to their excellent performance in thedisplays according to the invention.

IPS and FFS displays using dielectrically positive liquid crystals arewell known in the field and have been widely adopted for various typesof displays like e.g. desk top monitors and TV sets, but also for mobileapplications.

However, recently, IPS and in particular FFS displays usingdielectrically negative liquid crystals are widely adopted. The latterones are sometimes also called or UB-FFS (ultra bright FFS). Liquidcrystalline media used for UB-FFS have a dielectric anisotropy of −0.5or less, preferably −1.5 or less. Such displays are disclosed e.g. in US2013/0207038 A1. These displays are characterized by a markedlyincreased transmission compared to the previously used IPS- and FFSdisplays, which contain dielectrically positive liquid crystals.Displays using dielectrically negative liquid crystals, however, havethe severe disadvantage of requiring a higher operation voltage than therespective displays using dielectrically positive liquid crystals.

Liquid crystalline media used for HB-FFS (high brightness FFS)comprising both dielectrically negative and dielectrically positiveliquid crystalline compounds, respectively mesogenic compounds aredisclosed e.g. in US 2013/0207038 A1. These media feature rather largevalues of ε_(⊥) and of ε_(av.) already, however, their ratio of(ε_(⊥)/Δε) is relatively small. Liquid crystalline media used for HB-FFShave a dielectric anisotropy of 0.5 or more, preferably −1.5 or more.

According to the present application, however, the IPS or the FFSeffects with dielectrically positive liquid crystalline media in ahomogeneous alignment are preferred.

Industrial application of this effect in electro-optical displayelements requires LC phases which have to meet a multiplicity ofrequirements. Particularly important here are chemical resistance tomoisture, air and physical influences, such as heat, radiation in theinfrared, visible and ultraviolet regions, and direct (DC) andalternating (AC) electric fields.

Furthermore, LC phases which can be used industrially are required tohave a liquid-crystalline mesophase in a suitable temperature range andlow viscosity.

None of the series of compounds having a liquid-crystalline mesophasethat have been disclosed hitherto includes a single compound which meetsall these requirements. Mixtures of two to 25, preferably three to 18,compounds are therefore generally prepared in order to obtain substanceswhich can be used as LC phases.

Matrix liquid-crystal displays (MLC displays) are known. Non-linearelements which can be used for individual switching of the individualpixels are, for example, active elements (i.e. transistors). The term“active matrix” is then used, where in general use is made of thin-filmtransistors (TFTs), which are generally arranged on a glass plate assubstrate.

A distinction is made between two technologies: TFTs comprising compoundsemiconductors, such as, for example, CdSe, or metal oxides like ZnO orTFTs based on polycrystalline and, inter alia, amorphous silicon. Thelatter technology currently has the greatest commercial importanceworldwide.

The TFT matrix is applied to the inside of one glass plate of thedisplay, while the other glass plate carries the transparent counterelectrode on its inside. Compared with the size of the pixel electrode,the TFT is very small and has virtually no adverse effect on the image.This technology can also be extended to fully color-capable displays, inwhich a mosaic of red, green and blue filters is arranged in such a waythat a filter element is located opposite each switchable pixel.

The TFT displays most used hitherto usually operate with crossedpolarizers in transmission and are backlit. For TV applications, ECB (orVAN) cells or FFS cells are used, whereas monitors usually use IPS cellsor TN (twisted nematic) cells, and notebooks, laptops and mobileapplications usually use TN, VA or FFS cells.

The term MLC displays here encompasses any matrix display havingintegrated non-linear elements, i.e., besides the active matrix, alsodisplays with passive elements, such as varistors or diodes(MIM=metal-insulator-metal).

MLC displays of this type are particularly suitable for TV applications,monitors and notebooks or for displays with a high information density,for example in automobile manufacture or aircraft construction. Besidesproblems regarding the angle dependence of the contrast and the responsetimes, difficulties also arise in MLC displays due to insufficientlyhigh specific resistance of the liquid-crystal mixtures [TOGASHI, S.,SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E.,WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, September 1984: A210-288 Matrix LCD Controlled by Double Stage Diode Rings, pp. 141 ff.,Paris; STROMER, M., Proc. Eurodisplay 84, September 1984: Design of ThinFilm Transistors for Matrix Addressing of Television Liquid CrystalDisplays, pp. 145 ff., Paris]. With decreasing resistance, the contrastof an MLC display deteriorates. Since the specific resistance of theliquid-crystal mixture generally drops over the life of an MLC displayowing to interaction with the inside surfaces of the display, a high(initial) resistance is very important for displays that have to haveacceptable resistance values over a long operating period.

Displays which use the ECB effect have become established as so-calledVAN (vertically aligned nematic) displays, besides IPS displays (forexample: Yeo, S. D., Paper 15.3: “An LC Display for the TV Application”,SID 2004 International Symposium, Digest of Technical Papers, XXXV, BookII, pp. 758 and 759) and the long-known TN displays, as one of the threemore recent types of liquid-crystal display that are currently the mostimportant, in particular for television applications.

The most important designs may be mentioned here: MVA (multi-domainvertical alignment, for example: Yoshide, H. et al., Paper 3.1: “MVA LCDfor Notebook or Mobile PCs . . . ”, SID 2004 International Symposium,Digest of Technical Papers, XXXV, Book I, pp. 6 to 9, and Liu, C. T. etal., Paper 15.1: “A 46-inch TFT-LCD HDTV Technology . . . ”, SID 2004International Symposium, Digest of Technical Papers, XXXV, Book II, pp.750 to 753), PVA (patterned vertical alignment, for example: Kim, SangSoo, Paper 15.4: “Super PVA Sets New State-of-the-Art for LCD-TV”, SID2004 International Symposium, Digest of Technical Papers, XXXV, Book II,pp. 760 to 763) and ASV (advanced super view, for example: Shigeta,Mitzuhiro and Fukuoka, Hirofumi, Paper 15.2: “Development of HighQuality LCDTV”, SID 2004 International Symposium, Digest of TechnicalPapers, XXXV, Book II, pp. 754 to 757). More modern versions of the VAeffect, are the so called PAVA (photo-alignment VA) and PSVA(polymerstabilized VA).

In general form, the technologies are compared, for example, in Souk,Jun, SID Seminar 2004, Seminar M-6: “Recent Advances in LCD Technology”,Seminar Lecture Notes, M-6/1 to M-6/26, and Miller, Ian, SID Seminar2004, Seminar M-7: “LCD-Television”, Seminar Lecture Notes, M-7/1 toM-7/32. Although the response times of modern ECB displays have alreadybeen significantly improved by addressing methods with overdrive, forexample: Kim, Hyeon Kyeong et al., Paper 9.1: “A 57-in. Wide UXGATFT-LCD for HDTV Application”, SID 2004 International Symposium, Digestof Technical Papers, XXXV, Book I, pp. 106 to 109, the achievement ofvideo-compatible response times, in particular in the switching of greyshades, is still a problem which has not yet been solved to asatisfactory extent.

ECB displays, like ASV displays, use liquid-crystalline media havingnegative dielectric anisotropy (Δε), whereas TN and to date allconventional IPS displays use liquid-crystalline media having positivedielectric anisotropy. However, presently there is an increasing demandfor IPS and FFS displays utilizing dielectrically negative liquidcrystalline media.

In liquid-crystal displays of this type, the liquid crystals are used asdielectrics, whose optical properties change reversibly on applicationof an electrical voltage.

Since in displays in general, i.e. also in displays in accordance withthese mentioned effects, the operating voltage should be as low aspossible, use is made of liquid-crystal media which are generallypredominantly composed of liquid-crystal compounds, all of which havethe same sign of the dielectric anisotropy and have the highest possiblevalue of the dielectric anisotropy. In general, at most relatively smallproportions of neutral compounds and if possible no compounds having asign of the dielectric anisotropy which is opposite to that of themedium are employed. In the case of liquid-crystal media having negativedielectric anisotropy e.g. for ECB or UB-FFS displays, predominantlycompounds having negative dielectric anisotropy are thus employed. Therespective liquid-crystalline media employed generally consistpredominantly and usually even essentially of liquid-crystal compoundshaving negative dielectric anisotropy.

In the media used in accordance with the present application,significant amounts of dielectrically positive liquid-crystal compoundsand generally only very small amounts of dielectrically compounds oreven none at all are typically employed, since in general theliquid-crystal displays are intended to have the lowest possibleaddressing voltages. At the same time small amounts of dielectricallyneutral compounds may be beneficially used in some cases.

US 2013/0207038 A1 discloses liquid crystalline media for HB-FFSdisplays proposing to improve the performance of the FFS displays usingliquid crystals having a positive dielectric anisotropy by theadditional incorporation of dielectrically negative liquid crystals.This, however, leads to the necessity of a compensation of the negativecontribution of these compounds to the overall dielectric anisotropy ofthe resultant media. To this end, either the concentration of thedielectrically positive materials has to be increased, which, in turn,leaves less room for the use of dielectrically neutral compounds asdiluters in the mixtures, or, alternatively, compounds with a strongerpositive dielectric anisotropy have to be used. Both of thesealternatives have the strong drawback of increasing the response time ofthe liquid crystals in the displays.

Liquid crystalline media having a positive dielectric anisotropy for IPSand FFS displays have already been disclosed. In the following someexamples will be given.

CN 104232105 A discloses liquid crystalline media with a positivedielectric anisotropy having dielectric ratios (ε_(⊥)/Δε) of up to 0.7.

WO 2014/192390 also discloses liquid crystalline media with a positivedielectric anisotropy having rather high values of ε_(∥), but havingdielectric ratios (ε_(⊥)/Δε) of only about 0.5.

WO 2015/007131 discloses liquid crystalline media with a positivedielectric anisotropy, some of which have a dielectric ratio (ε_(⊥)/Δε)of about 0.7 and slightly above, up to 0.88.

Obviously, the range of the nematic phase of the liquid-crystal mixturemust be sufficiently broad for the intended application of the display.

The response times of the liquid-crystal media in the displays also haveto be improved, i.e. reduced. This is particularly important fordisplays for television or multimedia applications. In order to improvethe response times, it has repeatedly been proposed in the past tooptimize the rotational viscosity of the liquid-crystal media (γ₁), i.e.to achieve media having the lowest possible rotational viscosity.However, the results achieved here are inadequate for many applicationsand therefore make it appear desirable to find further optimizationapproaches.

Adequate stability of the media to extreme loads, in particular to UVexposure and heating, is very particularly important. In particular inthe case of applications in displays in mobile equipment, such as, forexample, mobile telephones, this may be crucial.

Besides their relatively poor transmission and their relatively longresponse times, the MLC displays disclosed hitherto, they have furtherdisadvantages. These are e.g. their comparatively low contrast, theirrelatively high viewing-angle dependence and the difficulty in thereproduction of grey scales in these displays, especially when observedfrom an oblique viewing angle, as well as their inadequate VHR and theirinadequate lifetime. The desired improvements of the transmission of thedisplays and of their response times are required in order to improvetheir energy efficiency, respectively their capacity to render rapidlymoving pictures.

There thus continues to be a great demand for MLC displays having veryhigh specific resistance at the same time as a large working-temperaturerange, short response times and a low threshold voltage, with the aid ofwhich various grey shades can be produced and which have, in particular,a good and stable VHR.

Thus, an object of the invention is to provide MLC displays, not onlyfor monitor and TV applications, but also for mobile applications suchas e.g. telephones and navigation systems, which are based on the ECB,IPS or FFS effect, that do not have the disadvantages indicated above,or only do so to a lesser extent, and at the same time have very highspecific resistance values. In particular, it must be ensured for mobiletelephones and navigation systems that they also work at extremely highand extremely low temperatures.

Upon further study of the specification and appended claims, otherobjects, aspects and advantages of the invention will become apparent.

Surprisingly, it has been found that it is possible to achieveliquid-crystal displays which have, in particular in IPS and FFSdisplays, a low threshold voltage with short response times, asufficiently broad nematic phase, favorable, relatively lowbirefringence (Δn) and, at the same time, a high transmission, goodstability to decomposition by heating and by UV exposure, and a stable,high VHR (voltage holding ratio) if use is made in these displayelements of nematic liquid-crystal mixtures which comprise at least onecompound, preferably two or more compounds of formula I, preferablyselected from the group of the compounds of the sub-formulae I-1, I-2,I-3 and I-4, particularly preferably the sub-formulate I-2 and/or I-3and/or I-4, more preferably I-2 and/or I-4, and preferably additionallyat least one compound, preferably two or more compounds, selected fromthe group of the compounds of the formulae Hand III, the formerpreferably of formula II-1 and/or II-2, and/or at least one compound,preferably two or more compounds selected from the group of formulae IVand/or V and, preferably, one or more compounds selected from the groupof formulae VII to IX (all formulae as defined herein below).

Media of this type can be used, in particular, for electro-opticaldisplays having active-matrix addressing for IPS- or FFS displays.

The invention thus relates to a liquid-crystalline medium on a mixtureof polar compounds comprising one or more compounds having either

-   -   a dielectric constant perpendicular to the director (ε_(⊥)) in        the range of 2 or more, to 8 or less, and a dielectric ratio of        the dielectric constant perpendicular to the director to the        dielectric anisotropy (ε_(⊥)/Δε) of 1.0 or more or    -   a dielectric constant perpendicular to the director (ε_(⊥)) of        8.0 or more, preferably of 26 or less and, preferably,        additionally also a dielectric ratio of the dielectric constant        perpendicular to the director to the dielectric anisotropy        (ε_(⊥)/Δε) of 1.0 or more.

The ratio of the dielectric constant perpendicular to the director tothe dielectric anisotropy (ε_(⊥)/Δε) of 1.0 or more corresponds to theratio of the dielectric constant parallel (ε_(∥)) to the director todielectric constant perpendicular (ε_(⊥)) to the director, i.e. to theratio of (ε_(∥)/ε_(⊥)) of 2.0 or less.

The media according to the present invention preferably additionallycomprise one or more compounds selected from the group of compounds offormulae II and III, preferably one or more compounds of formula II,more preferably in addition one or more compounds of formula III and,most preferably, additionally one or more compounds selected from thegroup of the compounds of formulae IV and V and, again preferably, oneor more compounds selected from the group of compounds of formulae VI toIX (all formulae as defined below).

The mixtures according to the invention exhibit very broad nematic phaseranges with clearing points ≥70° C., very favorable values for thecapacitive threshold, relatively high values for the holding ratio andat the same time good low-temperature stabilities at −20° C. and −30°C., as well as very low rotational viscosities. The mixtures accordingto the invention are furthermore distinguished by a good ratio ofclearing point and rotational viscosity and by a relatively highpositive dielectric anisotropy.

Now, it has been found surprisingly that LCs of the FFS type usingliquid crystals with positive dielectric anisotropy may be realizedusing specially selected liquid crystalline media. These media arecharacterized by a particular combination of physical properties. Mostdecisive amongst these are their dielectric properties and here a highaverage dielectric constant (ε_(av.)), a high dielectric constantperpendicular to the director of the liquid crystal molecules (ε_(⊥)), ahigh value of the dielectric anisotropy (Δε), and, in particular, arelatively high ratio of these latter two values: (ε_(⊥)/Δε).

Preferably, the liquid-crystalline media according to the presentinvention, on the one hand, have a value of the dielectric anisotropy of0.5 or more, preferably of 1.0 or more preferably of 1.5 or more. At theother hand, they preferably have a dielectric anisotropy of 26 or less.

Preferably, the liquid-crystalline media according to the presentinvention, on the one hand, have a value of the dielectric constantperpendicular to the director of 2 or more, more preferably of 8 or moreand, on the other hand preferably of 20 or less.

The liquid crystalline media according to the present inventionpreferably have a positive dielectric anisotropy, preferably in therange from 1.5 or more to 20.0 or less, more preferably in the rangefrom 3.0 or more to 8.0 or less and, most preferably in the range from4.0 or more to 7.0 or less.

The liquid crystalline media according to the present inventionpreferably have a dielectric constant perpendicular to the director ofthe liquid crystal molecules (ε_(⊥)) of 5.0 or more, more preferably of6.0 or more, more preferably of 7.0 or more, more preferably of 8.0 ormore, more preferably of 9 or more and, most preferably, of 10.0 ormore.

The liquid crystalline media according to the present inventionpreferably have a dielectric ratio (ε_(⊥)/Δε) of 1.0 or more, morepreferably of 1.5 or more and, most preferably, of 2.0 or more.

In a preferred embodiment of the present invention the liquidcrystalline medium preferably comprises

-   a) one or more compounds having both a high dielectric constant    perpendicular to the director and parallel to the director,    preferably selected from the group of compounds of formula I,    preferably in a concentration in the range from 1% to 60%, more    preferably in the range from 5% to 40%, particularly preferably in    the range from 8% to 35%, based on the total weight of the liquid    crystalline medium,

in which

denotes

denotes

-   n denotes 0 or 1,-   R¹¹ and R¹² independently of each other denote alkyl, alkoxy,    fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7 C    atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl    having 2 to 7 C atoms and preferably alkyl, alkoxy, alkenyl or    alkenyloxy, most preferably alkyl, alkoxy or alkenyloxy, and R¹¹    alternatively denotes R¹ and R¹² alternatively denotes X¹,-   R¹ denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy    preferably having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl    or fluorinated alkenyl having 2 to 7 C atoms and preferably alkyl or    alkenyl, and-   X¹ denotes F, Cl, fluorinated alkyl, fluorinated alkenyl,    fluorinated alkoxy or fluorinated alkenyloxy, the latter four groups    preferably having 1 to 4 C atoms, preferably F, Cl, CF₃ or OCF₃, in    particular for formulae I-1 and I-2 preferably F and for formula I-4    preferably OCF₃, and-   b) one or more dielectrically positive compounds selected from the    group of compounds of formulae II and III, preferably of compounds    having a dielectric anisotropy of greater than 3 each:

in which

-   R² denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy    having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl or    fluorinated alkenyl having 2 to 7 C atoms and preferably alkyl or    alkenyl,

on each appearance, independently of one another, denote

preferably

-   L²¹ and L²² denote H or F, preferably L²¹ denotes F,-   X² denotes halogen, halogenated alkyl or alkoxy having 1 to 3 C    atoms or halogenated alkenyl or alkenyloxy having 2 or 3 C atoms,    preferably F, Cl, —OCF₃, —O—CH₂CF₃, —O—CH═CH₂, —O—CH═CF₂ or —CF₃,    very preferably F, Cl, —O—CH═CF₂ or —OCF₃,-   m denotes 0, 1, 2 or 3, preferably 1 or 2 and particularly    preferably 1,-   R³ denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy    having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl or    fluorinated alkenyl having 2 to 7 C atoms and preferably alkyl or    alkenyl,

-   -   on each appearance, independently of one another, are

preferably

-   L³¹ and L³², independently of one another, denote H or F, preferably    L³¹ denotes F,-   X³ denotes halogen, halogenated alkyl or alkoxy having 1 to 3 C    atoms or halogenated alkenyl or alkenyloxy having 2 or 3 C atoms,    preferably F, Cl, —OCF₃, —OCHF₂, —O—CH₂CF₃, —O—CH═CF₂, —O—CH═CH₂ or    —CF₃, very preferably F, Cl, —O—CH═CF₂, —OCHF₂ or —OCF₃,-   Z³ denotes —CH₂CH₂—, —CF₂CF₂—, —COO—, trans-CH═CH—, trans-CF═CF—,    —CH₂O— or a single bond,    -   preferably —CH₂CH₂—, —COO—, trans-CH═CH— or a single bond, and        very preferably —COO—, trans-CH═CH— or a single bond, and-   n denotes 0, 1, 2 or 3, preferably 1, 2 or 3 and particularly    preferably 1, and-   c) optionally one or more dielectrically neutral compounds selected    from the group of formulae IV and V:

-   in which-   R⁴¹ and R⁴², independently of one another, have the meaning    indicated above for R² under formula II, preferably R⁴¹ denotes    alkyl and R⁴² denotes alkyl or alkoxy or R⁴¹ denotes alkenyl and R⁴²    denotes alkyl,

-   -   independently of one another and, if

occurs twice,

-   -   also these independently of one another, denote

-   -   preferably one or more of

-   -   denotes or denote,

-   Z⁴¹ and Z⁴², independently of one another and, if Z⁴¹ occurs twice,    also these independently of one another,    -   denote —CH₂CH₂—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH₂O—,        —CF₂O—, —C≡C— or a single bond, preferably one or more thereof        denotes/denote a single bond, and-   p denotes 0, 1 or 2, preferably 0 or 1, and-   R⁵¹ and R⁵², independently of one another, have one of the meanings    given for R²¹ and R²² and preferably denote alkyl having 1 to 7 C    atoms, preferably n-alkyl, particularly preferably n-alkyl having 1    to 5 C atoms, alkoxy having 1 to 7 C atoms, preferably n-alkoxy,    particularly preferably n-alkoxy having 2 to 5 C atoms, alkoxyalkyl,    alkenyl or alkenyloxy having 2 to 7 C atoms, preferably having 2 to    4 C atoms, preferably alkenyloxy,

-   -   if present, each, independently of one another, denote

preferably

preferably

denotes

and, if present,

preferably denotes

-   Z⁵¹ to Z⁵³ each, independently of one another, denote —CH₂—CH₂—,    —CH₂—O—, —CH═CH—, —C≡C—, —COO— or a single bond, preferably    —CH₂—CH₂—, —CH₂—O— or a single bond and particularly preferably a    single bond,-   i and j each, independently of one another, denote 0 or 1,-   (i+j) preferably denotes 0, 1 or 2, more preferably 0 or 1 and, most    preferably, 1.-   d) again optionally, either alternatively or additionally, one or    more dielectrically negative compounds selected from the group of    formulae VI to IX:

-   wherein-   R⁶¹ denotes an unsubstituted alkyl radical having 1 to 7 C atoms,    preferably a straight-chain alkyl radical, more preferably an    n-alkyl radical, most preferably propyl or pentyl, an unsubstituted    alkenyl radical having 2 to 7 C atoms, preferably a straight-chain    alkenyl radical, particularly preferably having 2 to 5 C atoms, an    unsubstituted alkoxy radical having 1 to 6 C atoms, or an    unsubstituted alkenyloxy radical having 2 to 6 C atoms,-   R⁶² denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an    unsubstituted alkoxy radical having 1 to 6 C atoms, or an    unsubstituted alkenyloxy radical having 2 to 6 C atoms, and-   I denotes 0 or 1,-   R⁷¹ denotes an unsubstituted alkyl radical having 1 to 7 C atoms,    preferably a straight-chain alkyl radical, more preferably an    n-alkyl radical, most preferably propyl or pentyl, or an    unsubstituted alkenyl radical having 2 to 7 C atoms, preferably a    straight-chain alkenyl radical, particularly preferably having 2 to    5 C atoms,-   R⁷² denotes an unsubstituted alkyl radical having 1 to 7 C atoms,    preferably having 2 to 5 C atoms, an unsubstituted alkoxy radical    having 1 to 6 C atoms, preferably having 1, 2, 3 or 4 C atoms, or an    unsubstituted alkenyloxy radical having 2 to 6 C atoms, preferably    having 2, 3 or 4 C atoms, and

denotes

-   R⁸¹ denotes an unsubstituted alkyl radical having 1 to 7 C atoms,    preferably a straight-chain alkyl radical, more preferably an    n-alkyl radical, most preferably propyl or pentyl, or an    unsubstituted alkenyl radical having 2 to 7 C atoms, preferably a    straight-chain alkenyl radical, particularly preferably having 2 to    5 C atoms,-   R⁸² denotes an unsubstituted alkyl radical having 1 to 7 C atoms,    preferably having 2 to 5 C atoms, an unsubstituted alkoxy radical    having 1 to 6 C atoms, preferably having 1, 2, 3 or 4 C atoms, or an    unsubstituted alkenyloxy radical having 2 to 6 C atoms, preferably    having 2, 3 or 4 C atoms,

denotes

preferably

more preferably

-   Z⁸ denotes —(C═O)—O—, —CH₂—O—, —CF₂—O— or —CH₂—CH₂—, preferably    —(C═O)—O— or —CH₂—O—, and-   o denotes 0 or 1,-   R⁹¹ and R⁹² independently of one another have the meaning given for    R⁷² above,-   R⁹¹ preferably denotes an alkyl radical having 2 to 5 C atoms,    preferably having 3 to 5 C atoms,-   R⁹² preferably denotes an alkyl or alkoxy radical having 2 to 5 C    atoms, more preferably an alkoxy radical having 2 to 4 C atoms, or    an alkenyloxy radical having 2 to 4 C atoms.

denotes

-   p and q independently of each other denote 0 or 1, and-   (p+q) preferably denotes 0 or 1, and in the case where

denotes

alternatively, preferably p=q=1.

The liquid-crystalline media in accordance with the present applicationpreferably have a nematic phase.

Preferably the compounds of formula I are selected from the group ofcompounds of formulae I-1 to I-4:

in which

-   R¹¹ and R¹² independently of each other denote alkyl, alkoxy,    fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7 C    atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl    having 2 to 7 C atoms, and preferably alkyl, alkoxy, alkenyl or    alkenyloxy, most preferably alkoxy or alkenyloxy,-   R¹ denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy    preferably having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl    or fluorinated alkenyl having 2 to 7 C atoms and preferably alkyl or    alkenyl, and-   X¹ denotes F, Cl, CN, NCS, fluorinated alkyl, fluorinated alkenyl,    fluorinated alkoxy or fluorinated alkenyloxy, the latter four groups    preferably having 1 to 4 C atoms, preferably F, Cl, CF₃ or OCF₃, in    particular for formulae I-1 and I-2 preferably F and for formula I-4    preferably OCF₃.

The compounds of formula I-3 are prepared according to WO 02/055463 andcompounds of the formula I-3 containing two alkoxy groups (R¹¹=>R¹—O;R¹²=>R²—O) are preferably prepared starting from the basic compounddibenzofuran according to the following scheme: (Scheme 1).

The compounds of formula I-3 containing one alkoxy group (R¹—O) and onealkyl group (R²), (R¹¹=>R¹—O; R¹²=>R²) are preferably prepared starting)from the basic compound dibenzofuran according to the following scheme:(Scheme 2).

The compounds of formula I-3 containing two alkyl groups (R¹¹=>R¹;R¹²=>R²) are preferably prepared starting from the basic compounddibenzofuran according to the following scheme: (Scheme 3).

The compounds of formula I-4 are preferably prepared e.g. according tothe following scheme.

The invention furthermore relates to the use of liquid-crystal mixturesand liquid-crystalline media according to the invention in IPS and FFSdisplays, in particular the use in SG-FFS displays containing aliquid-crystalline medium, for improving the response times and/or thetransmission.

The invention furthermore relates to a liquid-crystal display containinga liquid-crystalline medium according to the invention, in particular anIPS or FFS display, particularly preferably a FFS or SG-FFS display.

The invention furthermore relates to a liquid-crystal display of the IPSor FFS type comprising a liquid-crystal cell comprising two substrates,where at least one substrate is transparent to light and at least onesubstrate has an electrode layer, and a layer, located between thesubstrates, of a liquid-crystalline medium comprising a polymerizedcomponent and a low-molecular-weight component, where the polymerizedcomponent is obtainable by polymerization of one or more polymerizablecompounds in the liquid-crystalline medium between the substrates of theliquid-crystal cell, preferably with application of an electricalvoltage, and where the low-molecular-weight component is aliquid-crystal mixture according to the invention as described above andbelow.

The displays in accordance with the present invention are preferablyaddressed by an active matrix (active matrix LCDs, AMDs for short),preferably by a matrix of thin-film transistors (TFTs). However, theliquid crystals according to the invention can also be used in anadvantageous manner in displays having other known addressing means.

The invention furthermore relates to a process for the preparation of aliquid-crystalline medium according to the invention by mixing one ormore compounds of formula I, preferably selected from the group ofcompounds of formulae I-1 to I-4, with one or more low-molecular-weightliquid-crystalline compounds, or a liquid-crystal mixture and optionallywith further liquid-crystalline compounds and/or additives.

The following meanings apply above and below:

The term “FFS” is, unless indicated otherwise, used to represent FFS andSG-FFS displays.

The term “mesogenic group” is known to the person skilled in the art andis described in the literature, and denotes a group which, due to theanisotropy of its attracting and repelling interactions, essentiallycontributes to causing a liquid-crystalline (LC) phase inlow-molecular-weight or polymeric substances. Compounds containingmesogenic groups (mesogenic compounds) do not necessarily have to have aliquid-crystalline phase themselves. It is also possible for mesogeniccompounds to exhibit liquid-crystalline phase behavior only after mixingwith other compounds and/or after polymerization. Typical mesogenicgroups are, for example, rigid rod- or disc-shaped units. An overview ofthe terms and definitions used in connection with mesogenic orliquid-crystalline compounds is given in Pure Appl. Chem. 73(5), 888(2001) and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116,6340-6368.

The term “spacer group” or “spacer” for short, also referred to as “Sp”above and below, is known to the person skilled in the art and isdescribed in the literature, see, for example, Pure Appl. Chem. 73(5),888 (2001) and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004,116, 6340-6368. Unless indicated otherwise, the term “spacer group” or“spacer” above and below denotes a flexible group which connects themesogenic group and the polymerizable group(s) to one another in apolymerizable mesogenic compound.

For the purposes of this invention, the term “liquid-crystalline medium”is intended to denote a medium which comprises a liquid-crystal mixtureand one or more polymerizable compounds (such as, for example, reactivemesogens). The term “liquid-crystal mixture” (or “host mixture”) isintended to denote a liquid-crystalline mixture which consistsexclusively of unpolymerizable, low-molecular-weight compounds,preferably of two or more liquid-crystalline compounds and optionallyfurther additives, such as, for example, chiral dopants or stabilizers.

Particular preference is given to liquid-crystal mixtures andliquid-crystalline media which have a nematic phase, in particular atroom temperature.

In a preferred embodiment of the present invention, the liquid-crystalmedium comprises one or more dielectrically positive compounds having adielectric anisotropy of greater than 3, selected from the group of thecompounds of the formulae II-1 and II-2:

n which the parameters have the respective meanings indicated aboveunder formula II, and L²³ and L²⁴, independently of one another, denoteH or F, preferably L²³ denotes F, and

has one of the meanings given for

and, in the case of formulae II-1 and II-2, X² preferably denotes F orOCF₃, particularly preferably F, and, in the case of formula II-2,

independently of one another, preferably denote

and/or selected from the group of the compounds of the formulae III-1and III-2:

in which the parameters have the meanings given under formula III,and the media in accordance with the present invention may comprise,alternatively or in addition to the compounds of the formulae III-1and/or III-2, one or more compounds of the formula III-3

in which the parameters have the respective meanings indicated above,and the parameters L³¹ and L³², independently of one another and of theother parameters, denote H or F.

The liquid-crystal medium preferably comprises compounds selected fromthe group of the compounds of the formulae II-1 and II-2 in which L²¹and L²² and/or L²³ and L²⁴ both denote F.

In a preferred embodiment, the liquid-crystal medium comprises compoundsselected from the group of the compounds of the formulae II-1 and II-2in which L²¹, L²², L²³ and L²⁴ all denote F.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula II-1. The compounds of the formula II-1 are preferablyselected from the group of the compounds of the formulae II-1a to II-1e,preferably one or more compounds of formulae II-1a and/or II-1 b and/orII-1d, preferably of formula II-1a and/or II-1d or II-1b and/or II-1d,most preferably of formula II-1d:

in which the parameters have the respective meanings indicated above,and L²⁵ and L²⁶, independently of one another and of the otherparameters, denote H or F, and preferably in the formulae II-1a andII-1b, L²¹ and L²² both denote F, in the formulae II-1c and II-1d, L²¹and L²² both denote F and/or L²³ and L²⁴ both denote F, and in formulaII-1e, L²¹, L²² and L²³ denote F.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula II-2, which are preferably selected from the group of thecompounds of the formulae II-2a to II-2k, preferably one or morecompounds each of formulae II-2a and/or II-2h and/or II-2j:

in which the parameters have the respective meanings indicated above,and L²⁵ to L²⁸, independently of one another, denote H or F, preferablyL²⁷ and L²⁸ both denote H, particularly preferably L²⁶ denotes H.

The liquid-crystal medium preferably comprises compounds selected fromthe group of the compounds of the formulae II-2a to II-2k in which L²¹and L²² both denote F and/or L²³ and L²⁴ both denote F.

In a preferred embodiment, the liquid-crystal medium comprises compoundsselected from the group of the compounds of the formulae II-2a to II-2kin which L²¹, L²², L²³ and L²⁴ all denote F.

Especially preferred compounds of the formula II-2 are the compounds ofthe following formulae, particularly preferred of formulae II-2a-1and/or II-2h-1 and/or II-2k-2:

in which R² and X² have the meanings indicated above, and X² preferablydenotes F.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula III-1. The compounds of the formula III-1 are preferablyselected from the group of the compounds of the formulae III-1a toIII-1j, preferably from formulae III-1c, III-1f, III-1g and III-1j:

in which the parameters have the meanings given above and preferably inwhich the parameters have the respective meanings indicated above, theparameters L³³ and L³⁴, independently of one another and of the otherparameters, denote H or F, and the parameters L³⁵ and L³⁶, independentlyof one another and of the other parameters, denote H or F.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula III-1c, which are preferably selected from the group of thecompounds of the formulae III-1c-1 to III-1c-5, preferably of formulaeIII-1c-1 and/or III-1c-2, most preferably of formula III-1c-1:

in which R³ has the meaning indicated above.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula III-1f, which are preferably selected from the group of thecompounds of the formulae III-1f-1 to III-1f-6, preferably of formulaeIII-1f-1 and/or III-1f-2 and/or III-1f-3 and/or III-1f-6, morepreferably of formula III-1f-3 and/or III-1f-6, more preferably offormula III-1f-6:

in which R³ has the meaning indicated above.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula III-1g, which are preferably selected from the group of thecompounds of the formulae III-1g-1 to III-1g-5, preferably of formulaIII-1 g-3:

in which R³ has the meaning indicated above.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula III-1 h, which are preferably selected from the group of thecompounds of the formulae III-1 h-1 to III-1 h-3, preferably of theformula III-1 h-3:

in which the parameters have the meanings given above, and X³ preferablydenotes F.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula III-1j, which are preferably selected from the group of thecompounds of the formulae III-1i-1 and III-1i-2, preferably of theformula III-1i-2:

in which the parameters have the meanings given above, and X³ preferablydenotes F.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula III-1j, which are preferably selected from the group of thecompounds of the formulae III-1j-1 and III-1j-2, preferably of theformula III-1j-1:

in which the parameters have the meanings given above.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula III-2. The compounds of the formula III-2 are preferablyselected from the group of the compounds of the formulae III-2a andIII-2b, preferably of formula III-2b:

in which the parameters have the respective meanings indicated above,and the parameters L³³ and L³⁴, independently of one another and of theother parameters, denote H or F.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula III-2a, which are preferably selected from the group of thecompounds of the formulae III-2a-1 to III-2a-6:

in which R³ has the meaning indicated above.

The liquid-crystal medium preferably comprises one or more compounds ofthe formula III-2b, which are preferably selected from the group of thecompounds of the formulae III-2b-1 to III-2b-4, preferably III-2b-4:

in which R³ has the meaning indicated above.

Alternatively or in addition to the compounds of the formulae III-1and/or III-2, the media in accordance with the present invention maycomprise one or more compounds of the formula III-3

in which the parameters have the respective meanings indicated aboveunder formula III.

These compounds are preferably selected from the group of the formulaeIII-3a and III-3b:

in which R³ has the meaning indicated above.

The liquid-crystalline media in accordance with the present inventionpreferably comprise one or more dielectrically neutral compounds havinga dielectric anisotropy in the range from −1.5 to 3, preferably selectedfrom the group of the compounds of the formulae VI, VII, VIII and IX.

In the present application, the elements all include their respectiveisotopes. In particular, one or more H in the compounds may be replacedby D, and this is also particularly preferred in some embodiments. Acorrespondingly high degree of deuteration of the correspondingcompounds enables, for example, detection and recognition of thecompounds. This is very helpful in some cases, in particular in the caseof the compounds of formula I.

In the present application,

-   alkyl particularly preferably denotes straight-chain alkyl, in    particular CH₃—, C₂H₅—, n-C₃H₇—, n-C₄H₉— or n-C₅H₁₁—, and-   alkenyl particularly preferably denotes CH₂═CH—, E-CH₃—CH═CH—,    CH₂═CH—CH₂—CH₂—, E-CH₃—CH═CH—CH₂—CH₂— or E-(n-C₃H₇)—CH═CH—.

In a preferred embodiment of the present invention, the media accordingto the invention in each case comprise one or more compounds of formulaVI selected from the group of the compounds of the formulae VI-1 andVI-2, preferably one or more compounds each of formulae VI-1 and one ormore compounds of formula VI-2,

in which the parameters have the respective meanings given above underformula VI, and preferablyin formula VI-1

-   R⁶¹ and R⁶² independently of each other denote methoxy, ethoxy,    propoxy, butoxy (also or pentoxy, preferably ethoxy, butoxy or    pentoxy, more preferably ethoxy or butoxy and, most preferably    butoxy.    in formula VI-2-   R⁶¹ preferably denotes vinyl, 1-E-propenyl, but-4-en-1-yl,    pent-1-en-1-yl or pent-3-en-1-yl and n-propyl or n-pentyl and-   R⁶² denotes an unsubstituted alkyl radical having 1 to 7 C atoms,    preferably having 2 to 5 C atoms, or, preferably, an unsubstituted    alkoxy radical having 1 to 6 C atoms, particularly preferably having    2 or 4 C atoms and, most preferably, ethoxy, and

In a preferred embodiment of the present invention, the media accordingto the invention in each case comprise one or more compounds of formulaVII selected from the group of the compounds of the formulae VII-1 toVII-3, preferably one or more compounds each of the formulae VII-1 andone or more compounds of formula VII-2,

in which the parameters have the respective meanings given above underformula VII, and preferably

-   R⁷¹ denotes vinyl, 1-E-propenyl, but-4-en-1-yl, pent-1-en-1-yl or    pent-3-en-1-yl, n-propyl or n-pentyl and-   R⁷² denotes an unsubstituted alkyl radical having 1 to 7 C atoms,    preferably having 2 to 5 C atoms, or, preferably, an unsubstituted    alkoxy radical having 1 to 6 C atoms, particularly preferably having    2 or 4 C atoms and, most preferably, ethoxy.

In a preferred embodiment of the present invention, the media accordingto the invention in each case comprise one or more compounds of formulaVI-1 selected from the group of the following compounds:

In a preferred embodiment of the present invention, the media accordingto the invention in each case comprise one or more compounds of formulaVI-2 selected from the group of the following compounds:

In a preferred embodiment of the present invention, the media according

In a preferred embodiment of the present invention, the media accordingto the invention in each case comprise one or more compounds of formulaVII-1 selected from the group of the following compounds:

In a preferred embodiment of the present invention, the media accordingto the invention in each case comprise one or more compounds of formulaVII-2 selected from the group of the following compounds:

In addition to the compounds of formula I or the preferred sub-formulaethereof, the media in accordance with the present invention preferablycomprise one or more dielectrically negative compounds selected from thegroup of compounds of the formulae VI and VII preferably in a totalconcentration in the range from 5% or more to 90% or less, preferablyfrom 10% or more to 80% or less, particularly preferably from 20% ormore to 70% or less, based on the medium as a whole.

In a preferred embodiment of the present invention, the media accordingto the invention in each case comprise one or more compounds of formulaVIII selected from the group of the compounds of the formulae VIII-1 toVIII-3, preferably one or more compounds each of the formulae VIII-1and/or one or more compounds of formula VIII-3,

in which the parameters have the respective meanings given above underformula VIII, and preferably

-   R⁸¹ denotes vinyl, 1-E-propenyl, but-4-en-1-yl, pent-1-en-1-yl or    pent-3-en-1-yl, ethyl, n-propyl or n-pentyl, alkyl, preferably    ethyl, n-propyl or n-pentyl and-   R⁸² denotes an unsubstituted alkyl radical having 1 to 7 C atoms,    preferably having 1 to 5 C atoms or an unsubstituted alkoxy radical    having 1 to 6 C atoms.

In formulae VIII-1 and VIII-2 R⁸² preferably denotes alkoxy having 2 or4 C atoms and, most preferably, ethoxy, and in formula VIII-3 R⁸²preferably denotes preferably alkyl, preferably methyl, ethyl orn-propyl, most preferably methyl.

In a further preferred embodiment, the medium comprises one or morecompounds of formula IV

in which

-   R⁴¹ denotes an unsubstituted alkyl radical having 1 to 7 C atoms or    an unsubstituted alkenyl radical having 2 to 7 C atoms, preferably    an n-alkyl radical, particularly preferably having 2, 3, 4 or 5 C    atoms, and-   R⁴² denotes an unsubstituted alkyl radical having 1 to 7 C atoms, an    unsubstituted alkenyl radical having 2 to 7 C atoms, or an    unsubstituted alkoxy radical having 1 to 6 C atoms, both preferably    having 2 to 5 C atoms, an unsubstituted alkenyl radical preferably    having 2, 3 or 4 C atoms, more preferably a vinyl radical or    1-propenyl radical and in particular a vinyl radical.

In a particularly preferred embodiment, the medium comprises one or morecompounds of formula IV selected from the group of the compounds of theformulae IV-1 to IV-4, preferably of formula IV-1,

in which

-   alkyl and alkyl′, independently of one another, denote alkyl having    1 to 7 C atoms, preferably having 2 to 5 C atoms,-   alkenyl and alkenyl′, independently of one another, denote an    alkenyl radical having 2 to 5 C atoms, preferably having 2 to 4 C    atoms, particularly preferably 2 C atoms,-   alkenyl′ denotes an alkenyl radical having 2 to 5 C atoms,    preferably having 2 to 4 C atoms, particularly preferably having 2    to 3 C atoms, and-   alkoxy denotes alkoxy having 1 to 5 C atoms, preferably having 2 to    4 C atoms.

In a particularly preferred embodiment, the media according to theinvention comprise one or more compounds of formula IV-1 and/or one ormore compounds of formula IV-2.

In a further preferred embodiment, the medium comprises one or morecompounds of formula V.

The media according to the invention preferably comprise the followingcompounds in the total concentrations indicated, based on the medium asa whole:

-   -   1-60% by weight of one or more compounds selected from the group        of the compounds of formula I and    -   5-60% by weight of one or more compounds of formula II,        preferably selected from the group of the compounds of the        formulae II-1 and II-2 and/or    -   5-25% by weight of one or more compounds of formula III, and/or    -   5-45% by weight of one or more compounds of formula IV and/or    -   5-25% by weight of one or more compounds of formula V, and/or    -   5-25% by weight of one or more compounds of formula VI, and/or    -   5-20% by weight of one or more compounds of formula VII, and/or    -   5-30% by weight of one or more compounds of formula VIII,        preferably selected from the group of the compounds of the        formulae VIII-1 and VIII-2 and/or    -   0-60% by weight of one or more compounds of formula IX,    -   where the total content of all compounds of formulae I-IX which        are present in the medium preferably is 95% or more and, more        preferably 100%.

The latter condition holds for all media according to the presentapplication.

In a further preferred embodiment, the media in accordance with thepresent invention in addition to the compounds of formula I or thepreferred sub-formulae thereof, and to the compounds of formulae VIand/or VII and/or VIII and/or IX, preferably comprise one or moredielectrically neutral compounds selected from the group of compounds offormulae IV and V preferably in a total concentration in the range from5% or more to 90% or less, preferably from 10% or more to 80% or less,particularly preferably from 20% or more to 70% or less, based on themedium as a whole.

The medium according to the invention in a particularly preferredembodiment comprises, based on the medium as a whole:

-   -   one or more compounds of formula II in a total concentration in        the range from 5% or more to 50% or less, preferably in the        range from 10% or more to 40% or less, and/or    -   one or more compounds of formula VII-1 in a total concentration        in the range from 5% or more to 30% or less, and/or    -   one or more compounds of formula VII-2 in a total concentration        in the range from 3% or more to 30% or less.

Preferably the concentration of the compounds of formula I in the mediaaccording to the invention is in the range from 1% or more to 60% orless, more preferably from 5% or more to 40% or less, most preferablyfrom 8% or more to 35% or less, based on the medium as a whole.

In a preferred embodiment of the present invention the concentration ofthe compounds of formula II in the media is in the range from 3% or moreto 60% or less, more preferably from 5% or more to 55% or less, morepreferably from 10% or more to 50% or less and, most preferably, from15% or more to 45% or less, based on the medium as a whole.

In a preferred embodiment of the present invention the concentration ofthe compounds of formula VII in the media is in the range from 2% ormore to 50% or less, more preferably from 5% or more to 40% or less,more preferably from 10% or more to 35% or less and, most preferably,from 15% or more to 30% or less, based on the medium as a whole.

In a preferred embodiment of the present invention the concentration ofthe compounds of formula VII-1 in the media is in the range from 1% ormore to 40% or less, more preferably either from 2% or more to 35% orless, or, alternatively, from 15% or more to 25% or less, based on themedium as a whole.

In a preferred embodiment of the present invention the concentration ofthe compounds of formula VII-2 in the media, if present, is in the rangefrom 1% or more to 40% or less, more preferably from 5% or more to 35%or less and, most preferably, from 10% or more to 30% or less, based onthe medium as a whole.

The present invention also relates to electro-optical displays orelectro-optical components which contain liquid-crystalline mediaaccording to the invention. Preference is given to electro-opticaldisplays which are based on the VA, ECB, IPS or FFS effect, preferablyon the VA; IPS or FFS effect, and in particular those which areaddressed by means of an active-matrix addressing device.

Accordingly, the present invention likewise relates to the use of aliquid-crystalline medium according to the invention in anelectro-optical display or in an electro-optical component, and to aprocess for the preparation of the liquid-crystalline media according tothe invention, characterized in that one or more compounds of formula Iare mixed with one or more compounds of formula II, preferably with oneor more compounds of the sub-formulae II-1 and/or II-2 and/or with oneor more compounds of formula VII, preferably with one or more compoundsof the sub-formulae VII-1 and/or VII-2, particularly preferably one ormore compounds from two or more, preferably from three or more,different formulae thereof and very particularly preferably from allfour of these formulae II-1, II-2, VII-1 and VII-2 and one or morefurther compounds, preferably selected from the group of the compoundsof the formulae IV and V, more preferably with one or more compoundsboth of formula IV and of formula V.

In a further preferred embodiment, the medium comprises one or morecompounds of formula IV, selected from the group of the compounds of theformulae IV-2 and IV-3,

in which

-   alkyl and alkyl′, independently of one another, denote alkyl having    1 to 7 C atoms, preferably having 2 to 5 C atoms,-   alkoxy denotes alkoxy having 1 to 5 C atoms, preferably having 2 to    4 C atoms.

In a further preferred embodiment, the medium comprises one or morecompounds of formula V selected from the group of the compounds of theformulae V-1 and V-2, preferably of formulae V-1,

in which the parameters have the meanings given above under formula V,and preferably

-   R⁵¹ denotes alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C    atoms, and-   R⁵² denotes alkyl having 1 to 7 C atoms, alkenyl having 2 to 7 C    atoms or alkoxy having 1 to 6 C atoms, preferably alkyl or alkenyl,    particularly preferably alkyl.

In a further preferred embodiment, the medium comprises one or morecompounds of formula V-1 selected from the group of the compounds of theformulae V-1a and V-1b,

in which

-   alkyl and alkyl′, independently of one another, denote alkyl having    1 to 7 C atoms, preferably having 2 to 5 C atoms, and-   alkenyl denotes alkenyl having 2 to 7 C atoms, preferably having 2    to 5 C atoms.

In addition, the present invention relates to a method for the reductionof the wavelength dispersion of the birefringence of aliquid-crystalline medium which comprises one or more compounds offormula II, optionally one or more compounds selected from the group ofthe compounds of the formulae VII-1 and VII-2 and/or one or morecompounds of formula IV and/or one or more compounds of formula V,characterized in that one or more compounds of formula I are used in themedium.

Besides compounds of the formulae I to V, other constituents may also bepresent, for example in an amount of up to 45%, but preferably up to35%, in particular up to 10%, of the mixture as a whole.

The media according to the invention may optionally also comprise adielectrically positive component, whose total concentration ispreferably 20% or less, more preferably 10% or less, based on the entiremedium.

In a preferred embodiment, the liquid-crystal media according to theinvention comprise in total, based on the mixture as a whole,

1% or more to 20% or less, preferably 2% or more to 15% or less,particularly preferably 3% or more to 12% or less, of the compound offormula I.

20% or more to 50% or less, preferably 25% or more to 45% or less,particularly preferably 30% or more to 40% or less, of compounds offormulae II and/or III, and

0% or more to 35% or less, preferably 2% or more to 30% or less,particularly preferably 3% or more to 25% or less, of compounds offormulae IV and/or V, and

5% or more to 50% or less 10% or more to 45% or less, preferably 15% ormore to 40% or less of compounds of the formulae VI and/or VII and/orVIII and/or IX.

The liquid-crystal media in accordance with the present invention maycomprise one or more chiral compounds.

Particularly preferred embodiments of the present invention meet one ormore of the following conditions,

where the acronyms (abbreviations) are explained in Tables A to C andillustrated by examples in Table D.

Preferably the media according to the present invention fulfil one ormore of the following conditions (percentages are based on the medium asa whole).

-   i. The liquid-crystalline medium has a birefringence of 0.060 or    more, particularly preferably 0.070 or more.-   ii. The liquid-crystalline medium has a birefringence of 0.200 or    less, particularly preferably 0.180 or less.-   iii. The liquid-crystalline medium has a birefringence in the range    from 0.090 or more to 0.120 or less.-   iv. The liquid-crystalline medium comprises one or more particularly    preferred compounds of formula I-1.-   v. The total concentration of the compounds of formula II in the    mixture as a whole is 25% or more, preferably 30% or more, and is    preferably in the range from 25% or more to 49% or less,    particularly preferably in the range from 29% or more to 47% or    less, and very particularly preferably in the range from 37% or more    to 44% or less.-   vi. The liquid-crystalline medium comprises one or more compounds of    formula IV selected from the group of the compounds of the following    formulae: CC-n-V and/or CC-n-Vm and/or CC-V-V and/or CC-V-Vn and/or    CC-nV-Vn, particularly preferably CC-3-V, preferably in a    concentration of up to 60% or less, particularly preferably up to    50% or less, and optionally additionally CC-3-V1, preferably in a    concentration of up to 15% or less, and/or CC-4-V, preferably in a    concentration of up to 24% or less, particularly preferably up to    30% or less.-   vii. The media comprise the compound of formula CC-n-V, preferably    CC-3-V, preferably in a concentration of 1% or more to 60% or less,    more preferably in a concentration of 3% or more to 35% or less.-   viii. The total concentration of the compounds of formula CC-3-V in    the mixture as a whole preferably either is 15% or less, preferably    10% or less or 20% or more, preferably 25% or more.-   ix. The total concentration of the compounds of formula Y-nO-Om in    the mixture as a whole is 2% or more to 30% or less, preferably 5%    or more to 15% or less.-   x. The total concentration of the compounds of formula CY-n-Om in    the mixture as a whole is 5% or more to 60% or less, preferably 15%    or more to 45% or less.-   xi. The total concentration of the compounds of formula CCY-n-Om    and/or CCY-n-m, preferably of CCY-n-Om, in the mixture as a whole is    5% or more to 40% or less, preferably 1% or more to 25% or less.-   xii. The total concentration of the compounds of formula CLY-n-Om in    the mixture as a whole is 5% or more to 40% or less, preferably 10%    or more to 30% or less.-   xiii. The liquid-crystalline medium comprises one or more compounds    of formula IV, preferably of the formulae IV-1 and/or IV-2,    preferably in a total concentration of 1% or more, in particular 2%    or more, and very particularly preferably 3% or more to 50% or less,    preferably 35% or less.-   xiv. The liquid-crystalline medium comprises one or more compounds    of formula V, preferably of the formulae V-1 and/or V-2, preferably    in a total concentration of 1% or more, in particular 2% or more,    and very particularly preferably 15% or more to 35% or less,    preferably to 30% or less.-   xv. The total concentration of the compounds of formula CCP-V-n,    preferably CCP-V-1, in the mixture as a whole preferably is 5% or    more to 30% or less, preferably 15% or more to 25% or less.-   xvi. The total concentration of the compounds of formula CCP-V2-n,    preferably CCP-V2-1, in the mixture as a whole preferably is 1% or    more to 15% or less, preferably 2% or more to 10% or less.

The invention furthermore relates to an electro-optical display havingactive-matrix addressing based on the VA, ECB, IPS, FFS or UB-FFSeffect, characterized in that it contains, as dielectric, aliquid-crystalline medium in accordance with the present invention.

The liquid-crystal mixture preferably has a nematic phase range having awidth of at least 70 degrees.

The rotational viscosity γ₁ is preferably 350 mPa·s or less, preferably250 mPa·s or less and, in particular, 150 mPa·s or less.

The mixtures according to the invention are suitable for all IPS andFFS-TFT applications using dielectrically positive liquid crystallinemedia, such as, e.g. SG-FFS.

The liquid-crystalline media according to the invention preferablyvirtually completely consist of 4 to 15, in particular 5 to 12, andparticularly preferably 10 or less, compounds. These are preferablyselected from the group of the compounds of the formula I, II III, IV,V, VI, VII, VIII and IX.

The liquid-crystalline media according to the invention may optionallyalso comprise more than 18 compounds. In this case, they preferablycomprise 18 to 25 compounds.

In a preferred embodiment, the liquid-crystal media according to theinvention predominantly comprise, preferably consist essentially of and,most preferably, virtually completely consist of compounds, which do notcomprise a cyano group.

In a preferred embodiment, the liquid-crystal media according to theinvention comprise compounds selected from the group of the compounds ofthe formulae I, II, and III, IV and V and VI to IX, preferably selectedfrom the group of the compounds of the formulae I-1, I-2, I-3, I-4,II-1, II-2, III-1, III-2, IV, V, VII-1, VII-2, VIII and IX; theypreferably predominantly comprise, particularly preferably consistessentially of, and very particularly preferably virtually completelyconsist of the compounds of the said formulae.

The liquid-crystal media according to the invention preferably have anematic phase from in each case at least −10° C. or less to 70° C. ormore, particularly preferably from −20° C. or less to 80° C. or more,very particularly preferably from −30° C. or less to 85° C. or more andmost preferably from −40° C. or less to 90° C. or more.

The expression “have a nematic phase” here means, on the one hand, thatno smectic phase and no crystallization are observed at low temperaturesat the corresponding temperature and, on the other hand, that noclearing occurs on heating out of the nematic phase. The investigationat low temperatures is carried out in a flow viscometer at thecorresponding temperature and checked by storage in test cells having acell thickness corresponding to the electro-optical application for atleast 100 hours. If the storage stability at a temperature of −20° C. ina corresponding test cell is 1000 h or more, the medium is regarded asstable at this temperature. At temperatures of −30° C. and −40° C., thecorresponding times are 500 h and 250 h respectively. At hightemperatures, the clearing point is measured in capillaries byconventional methods.

In a preferred embodiment, the liquid-crystal media according to theinvention are characterized by optical anisotropy values in the moderateto low range. The birefringence values are preferably in the range from0.075 or more to 0.130 or less, particularly preferably in the rangefrom 0.085 or more to 0.120 or less and very particularly preferably inthe range from 0.090 or more to 0.115 or less.

In this embodiment, the liquid-crystal media according to the inventionhave a positive dielectric anisotropy and relatively high absolutevalues of the dielectric anisotropy Δε, which preferably is in the rangefrom 0.5 or more, preferably of 1.0 or more, more preferably of 2.0 ormore to 20 or less, more preferably to 15 or less, more preferably from3.0 or more to 10 or less, particularly preferably from 4.0 or more to9.0 or less and very particularly preferably from 4.5 or more to 8.0 orless.

The liquid-crystal media according to the invention preferably haverelatively low values for the threshold voltage (V₀) in the range from1.0 V or more to 2.5 V or less, preferably from 1.2 V or more to 2.2 Vor less, particularly preferably from 1.3 V or more to 2.0 V or less.

In a further preferred embodiment, the liquid-crystal media according tothe invention preferably have relatively high values of the averagedielectric constant (ε_(av.)≡(ε_(∥)+2ε_(⊥))/3) which are preferably inthe range from 8.0 or more to 25.0 or less, preferably from 8.5 or moreto 20.0 or less, still more preferably from 9.0 or more to 19.07 orless, particularly preferably from 10.0 or more to 18.0 or less and veryparticularly preferably from 11.0 or more to 16.5 or less.

In addition, the liquid-crystal media according to the invention havehigh values for the VHR in liquid-crystal cells.

In freshly filled cells at 20° C. in the cells, these VHR are greaterthan or equal to 95%, preferably greater than or equal to 97%,particularly preferably greater than or equal to 98% and veryparticularly preferably greater than or equal to 99%, and after 5minutes in the oven at 100° C. in the cells, these are greater than orequal to 90%, preferably greater than or equal to 93%, particularlypreferably greater than or equal to 96% and very particularly preferablygreater than or equal to 98%.

In general, liquid-crystal media having a low addressing voltage orthreshold voltage here have a lower VHR than those having a higheraddressing voltage or threshold voltage, and vice versa.

These preferred values for the individual physical properties arepreferably also in each case maintained by the media according to theinvention in combination with one another.

In the present application, the term “compounds”, also written as“compound(s)”, means both one and also a plurality of compounds, unlessexplicitly indicated otherwise.

In a preferred embodiment, the liquid-crystalline media according to theinvention comprise:

one or more compounds of formula I and one or more compounds of formulaII, preferably of the formulae PUQU-n-F, CDUQU-n-F, APUQU-n-F andPGUQU-n-F (defined below), and/or

one or more compounds of formula III, preferably of the formulaeCCP-n-OT, CGG-n-F, and CGG-n-OD (defined below), and/or

one or more compounds of formulae IV and/or V, preferably of theformulae CC-n-V, CCP-n-m, CCP-V-n, CCP-V2-n and CGP-n-n (defined below),and/or

one or more compounds of formula VI, preferably of the formulae Y-n-Om,Y-nO-Om and/or CY-n-Om (defined below), especially selected from thegroup of the compounds of the formulae Y-3-O1, Y-4O-O4, CY-3-O2,CY-3-O4, CY-5-O2 and CY-5-O4 (defined below), and/oroptionally, preferably obligatorily, one or more compounds of formulaVII-1, preferably selected from the group of the compounds of theformulae CCY-n-m and CCY-n-Om (defined below), preferably of formulaCCY-n-Om, preferably selected from the group of the compounds of theformulae CCY-3-O2, CCY-2-O2, CCY-3-O1, CCY-3-O3, CCY-4-O2, CCY-3-O2 andCCY-5-O2 (defined below), and/oroptionally, preferably obligatorily, one or more compounds of formulaVII-2, preferably of formula CLY-n-Om (defined below), preferablyselected from the group of the compounds of the formulae CLY-2-O4,CLY-3-O2, CLY-3-O3 (defined below), and/orone or more compounds of formula VIII, preferably of the formulaeCZY-nO-n and CCOY-n-m (defined below), and/orone or more compounds of formula IX, preferably of the formula PYP-n-m(defined below), and/oroptionally, preferably obligatorily, one or more compounds of formulaIV, preferably selected from the group of the compounds of the formulaeCC-n-V, CC-n-Vm and CC-nV-Vm, preferably CC-3-V, CC-3-V1, CC-4-V, CC-5-Vand CC-V-V (defined below), particularly preferably selected from thegroup of the compounds CC-3-V, CC-3-V1, CC-4-V and CC-V-V, veryparticularly preferably the compound CC-3-V, and optionally additionallythe compound(s) CC-4-V and/or CC-3-V1 and/or CC-V-V, and/oroptionally, preferably obligatorily, one or more compounds of formula V,preferably of the formulae CCP-V-1 and/or CCP-V2-1 (defined below).

In a specific preferred embodiment of the present invention, the mediaaccording to the invention comprise one or more compounds of formula IX,

The compounds of formula IX, are also highly suitable as stabilizers inliquid-crystal mixtures, especially in case p=q=1 and ringA⁹=1,4-phenylene. In particular, they stabilize the VHR of the mixturesagainst UV exposure.

In a preferred embodiment the media according to the invention compriseone or more compounds of formula IX selected from one or more formulaeof the group of the compounds of the formulae IX-1 to IX-4, veryparticularly preferably of the formulae IX-1 to IX-3,

in which the parameters have the meanings given under formula IX.

In a further preferred embodiment, the medium comprises one or morecompounds of formula IX-3, preferably of formula IX-3-a,

in which

-   alkyl and alkyl′, independently of one another, denote alkyl having    1 to 7 C atoms, preferably having 2 to 5 C atoms.

In case the compounds of formula IX are used in the liquid crystallinemedia according to the present application, they are preferably presentin a concentration of 20% or less, more preferably of 10% or less and,most preferably, of 5% or less, based on the medium as a whole, and forthe individual i.e. (homologous) compounds preferably in a concentrationof 10% or less and, more preferably, of 5% or less, based on the mediumas a whole.

For the present invention, the following definitions apply in connectionwith the specification of the constituents of the compositions, unlessindicated otherwise in individual cases:

-   -   “comprise”: the concentration of the constituents in question in        the composition is preferably 5% or more, particularly        preferably 10% or more, very particularly preferably 20% or        more,    -   “predominantly consist of”: the concentration of the        constituents in question in the composition is preferably 50% or        more, particularly preferably 55% or more and very particularly        preferably 60% or more,    -   “essentially consist of”: the concentration of the constituents        in question in the composition is preferably 80% or more,        particularly preferably 90% or more and very particularly        preferably 95% or more, and    -   “virtually completely consist of”: the concentration of the        constituents in question in the composition is preferably 98% or        more, particularly preferably 99% or more and very particularly        preferably 100.0%.

This applies both to the media as compositions with their constituents,which can be components and compounds, and also to the components withtheir constituents, the compounds. Only in relation to the concentrationof an individual compound relative to the medium as a whole does theterm comprise mean: the concentration of the compound in question ispreferably 1% or more, particularly preferably 2% or more, veryparticularly preferably 4% or more.

For the present invention, “≤” means less than or equal to, preferablyless than, and “≥” means greater than or equal to, preferably greaterthan.

For the present invention,

denote trans-1,4-cyclohexylene, and

denote 1,4-phenylene.

For the present invention, the expression “dielectrically positivecompounds” means compounds having a Δε of >1.5, the expression“dielectrically neutral compounds” means those where −1.5≤Δε≤1.5 and theexpression “dielectrically negative compounds” means those whereΔε<−1.5. The dielectric anisotropy of the compounds is determined hereby dissolving 10% of the compounds in a liquid-crystalline host anddetermining the capacitance of the resultant mixture in each case in atleast one test cell having a cell thickness of 20 μm with homeotropicand with homogeneous surface alignment at 1 kHz. The measurement voltageis typically 0.5 V to 1.0 V, but is always lower than the capacitivethreshold of the respective liquid-crystal mixture investigated.

The host mixture used for dielectrically positive and dielectricallyneutral compounds is ZLI-4792 and that used for dielectrically negativecompounds is ZLI-2857, both from Merck KGaA, Germany. The values for therespective compounds to be investigated are obtained from the change inthe dielectric constant of the host mixture after addition of thecompound to be investigated and extrapolation to 100% of the compoundemployed. The compound to be investigated is dissolved in the hostmixture in an amount of 10%. If the solubility of the substance is toolow for this purpose, the concentration is halved in steps until theinvestigation can be carried out at the desired temperature.

The liquid-crystal media according to the invention may, if necessary,also comprise further additives, such as, for example, stabilizersand/or pleo-chroitic, e.g. dichroitic, dyes and/or chiral dopants in theusual amounts. The amount of these additives employed is preferably intotal 0% or more to 10% or less, based on the amount of the entiremixture, particularly preferably 0.1% or more to 6% or less. Theconcentration of the individual compounds employed is preferably 0.1% ormore to 3% or less. The concentration of these and similar additives isgenerally not taken into account when specifying the concentrations andconcentration ranges of the liquid-crystal compounds in theliquid-crystal media.

In a preferred embodiment, the liquid-crystal media according to theinvention comprise a polymer precursor which comprises one or morereactive compounds, preferably reactive mesogens, and, if necessary,also further additives, such as, for example, polymerization initiatorsand/or polymerization moderators, in the usual amounts. The amount ofthese additives employed is in total 0% or more to 10% or less, based onthe amount of the entire mixture, preferably 0.1% or more to 2% or less.The concentration of these and similar additives is not taken intoaccount when specifying the concentrations and concentration ranges ofthe liquid-crystal compounds in the liquid-crystal media.

The compositions consist of a plurality of compounds, preferably 3 ormore to 30 or fewer, particularly preferably 6 or more to 20 or fewerand very particularly preferably 10 or more to 16 or fewer compounds,which are mixed in a conventional manner. In general, the desired amountof the components used in lesser amount is dissolved in the componentsmaking up the principal constituent of the mixture. This isadvantageously carried out at elevated temperature. If the selectedtemperature is above the clearing point of the principal constituent,completion of the dissolution operation is particularly easy to observe.However, it is also possible to prepare the liquid-crystal mixtures inother conventional ways, for example using pre-mixes or from a so-called“multi-bottle system”.

The mixtures according to the invention exhibit very broad nematic phaseranges having clearing points of 65° C. or more, very favorable valuesfor the capacitive threshold, relatively high values for the holdingratio and at the same time very good low-temperature stabilities at −30°C. and −40° C. Furthermore, the mixtures according to the invention aredistinguished by low rotational viscosities γ₁.

It goes without saying to the person skilled in the art that the mediaaccording to the invention for use in VA, IPS, FFS or PALC displays mayalso comprise compounds in which, for example, H, N, O, Cl, F have beenreplaced by the corresponding isotopes.

The structure of the liquid-crystal displays according to the inventioncorresponds to the usual geometry, as described, for example, in EP-A 0240 379.

The liquid-crystal phases according to the invention can be modified bymeans of suitable additives in such a way that they can be employed inany type of, for example, IPS and FFS LCD display that has beendisclosed to date.

Table E below indicates possible dopants which can be added to themixtures according to the invention. If the mixtures comprise one ormore dopants, it is (they are) employed in amounts of 0.01% to 4%,preferably 0.1% to 1.0%.

Stabilizers which can be added, for example, to the mixtures accordingto the invention, preferably in amounts of 0.01% to 6%, in particular0.1% to 3%, are shown below in Table F.

For the purposes of the present invention, all concentrations are,unless explicitly noted otherwise, indicated in percent by weight andrelate to the corresponding mixture as a whole or to the respectivemixture component, again as a whole, unless explicitly indicatedotherwise. In this context the term “mixture” describes the liquidcrystalline medium.

All temperature values indicated in the present application, such as,for example, the melting point T(C,N), the smectic (S) to nematic (N)phase transition T(S,N) and the clearing point T(N,I), are indicated indegrees Celsius (° C.) and all temperature differences arecorrespondingly indicated in differential degrees (° or degrees), unlessexplicitly indicated otherwise.

For the present invention, the term “threshold voltage” relates to thecapacitive threshold (V₀), also known as the Freedericks threshold,unless explicitly indicated otherwise.

All physical properties are and have been determined in accordance with“Merck Liquid Crystals, Physical Properties of Liquid Crystals”, statusNovember 1997, Merck KGaA, Germany, and apply for a temperature of 20°C., and Δn is determined at 436 nm, 589 nm and at 633 nm, and Δε at 1kHz, unless explicitly indicated otherwise in each case.

The electro-optical properties, for example the threshold voltage (V₀)(capacitive measurement), are, as is the switching behavior, determinedin test cells produced at Merck Japan. The measurement cells havesoda-lime glass substrates and are constructed in an ECB or VAconfiguration with polyimide alignment layers (SE-1211 with diluent **26(mixing ratio 1:1), both from Nissan Chemicals, Japan), which have beenrubbed perpendicularly to one another and effect homeotropic alignmentof the liquid crystals. The surface area of the transparent, virtuallysquare ITO electrodes is 1 cm².

Unless indicated otherwise, a chiral dopant is not added to theliquid-crystal mixtures used, but the latter are also particularlysuitable for applications in which doping of this type is necessary.

The rotational viscosity is determined using the rotating permanentmagnet method and the flow viscosity in a modified Ubbelohde viscometer.For liquid-crystal mixtures ZLI-2293, ZLI-4792 and MLC-6608, allproducts from Merck KGaA, Darmstadt, Germany, the rotational viscosityvalues determined at 20° C. are 161 mPa·s, 133 mPa·s and 186 mPa·srespectively, and the flow viscosity values (ν) are 21 mm²·s⁻¹, 14mm²·s⁻¹ and 27 mm²·s⁻¹, respectively.

The dispersion of the materials may for practical purposes beconveniently characterized in the following way, which is usedthroughout this application unless explicitly stated otherwise. Thevalues of the birefringence are determined at a temperature of 20° C. atseveral fixed wavelengths using a modified Abbé refractometer withhomeotropically aligning surfaces on the sides of the prisms in contactwith the material. The birefringence values are determined at thespecific wavelength values of 436 nm (respective selected spectral lineof a low pressure mercury lamp), 589 nm (sodium “D” line) and 633 nm(wavelength of a HE-Ne laser (used in combination with anattenuator/diffusor in order to prevent damage to the eyes of theobservers. In the following table Δn is given at 589 nm and Δ(Δn) isgiven as Δ(Δn)=Δn(436 nm)−Δn(633 nm).

The following symbols are used, unless explicitly indicated otherwise:

-   V₀ threshold voltage, capacitive [V] at 20° C.,-   n_(e) extraordinary refractive index measured at 20° C. and 589 nm,-   n_(o) ordinary refractive index measured at 20° C. and 589 nm,-   Δn optical anisotropy measured at 20° C. and 589 nm,-   λ wavelength λ [nm],-   Δn(λ) optical anisotropy measured at 20° C. and wavelength λ,-   Δ(Δn) change in optical anisotropy defined as: Δn(20° C., 436    nm)−Δn(20° C., 633 nm),-   Δ(Δn*) “relative change in optical anisotropy” defined as:    Δ(Δn)/Δn(20° C., 589 nm),-   ε_(⊥) dielectric susceptibility perpendicular to the director at    20° C. and 1 kHz,-   ε_(∥) dielectric susceptibility parallel to the director at 20° C.    and 1 kHz,-   Δε dielectric anisotropy at 20° C. and 1 kHz,-   T(N,I) or cl.p.clearing point [° C.],-   ν flow viscosity measured at 20° C. [mm²·s⁻¹],-   γ₁ rotational viscosity measured at 20° C. [mPa·s],-   k₁₁ elastic constant, “splay” deformation at 20° C. [pN],-   k₂₂ elastic constant, “twist” deformation at 20° C. [pN],-   k₃₃ elastic constant, “bend” deformation at 20° C. [pN],-   LTS low-temperature stability of the phase, determined in test    cells,-   VHR voltage holding ratio,-   ΔVHR decrease in the voltage holding ratio, and-   S_(rel) relative stability of the VHR,

The following examples explain the present invention without limitingit. However, they show the person skilled in the art preferred mixtureconcepts with compounds preferably to be employed and the respectiveconcentrations thereof and combinations thereof with one another. Inaddition, the examples illustrate the properties and propertycombinations that are accessible.

For the present invention and in the following examples, the structuresof the liquid-crystal compounds are indicated by means of acronyms, withthe transformation into chemical formulae taking place in accordancewith Tables A to C below. All radicals C_(n)H_(2n+1), C_(m)H_(2m+1) andC_(l)H_(2l+1) or C_(n)H_(2n), C_(m)H_(2m) and C_(l)H_(2l) arestraight-chain alkyl radicals or alkylene radicals, in each case havingn, m and I C atoms respectively. Preferably n, m and I are independentlyof each other 1, 2, 3, 4, 5, 6, or 7. Table A shows the codes for thering elements of the nuclei of the compound, Table B lists the bridgingunits, and Table C lists the meanings of the symbols for the left- andright-hand end groups of the molecules. The acronyms are composed of thecodes for the ring elements with optional linking groups, followed by afirst hyphen and the codes for the left-hand end group, and a secondhyphen and the codes for the right-hand end group. Table D showsillustrative structures of compounds together with their respectiveabbreviations.

TABLE A Ring elements C

D

DI

A

AI

P

G

GI

U

UI

Y

P(F, Cl)Y

P(Cl,F)Y

np

n3f

nN3fI

th

thI

tH2f

tH2fI

o2f

o2fI

dh

B

K

KI

L

LI

F

FI

TABLE B Bridging units E —CH₂—CH₂— V —CH═CH— T —C≡C— W —CF₂—CF₂— B—CF═CF— Z —CO—O— ZI —O—CO— X —CF═CH— XI —CH═CF— O —CH₂—O— OI —O—CH₂— Q—CF₂—O— QI —O—CF₂—

TABLE C End groups On the left individually or in combination On theright individually or in combination -n- C_(n)H_(2n+1)— -n—C_(n)H_(2n+1) -nO- C_(n)H_(2n+1)—O— -nO —O—C_(n)H_(2n+1) -V- CH₂═CH— -V—CH═CH₂ -nV- C_(n)H_(2n+1)—CH═CH— -nV —C_(n)H_(2n)—CH═CH₂ -Vn-CH₂═CH—C_(n)H_(2n)— -Vn —CH═CH—C_(n)H_(2n+1) -nVm-C_(n)H_(2n+1)—CH═CH—C_(m)H_(2m)— -nVm —C_(n)H_(2n)—CH═CH—C_(m)H_(2m+1)-N- N≡C— -N —C≡N -S- S═C═N— -S —N═C═S -F- F— -F —F -CL- Cl— -CL —Cl -M-CFH₂— -M —CFH₂ -D- CF₂H— -D —CF₂H -T- CF₃— -T —CF₃ -MO- CFH₂O— -OM—OCFH₂ -DO- CF₂HO— -OD —OCF₂H -TO- CF₃O— -OT —OCF₃ -A- H—C≡C— -A —C≡C—H-nA- C_(n)H_(2n+1)—C≡C— -An —C≡C—C_(n)H_(2n+1) -NA- N≡C—C≡C— -AN—C≡C—C≡N On the left only in combination On the right only incombination - . . . n . . . - —C_(n)H_(2n)— - . . . n . . .—C_(n)H_(2n)— - . . . M . . . - —CFH— - . . . M . . . —CFH— - . . . D .. . - —CF₂— - . . . D . . . —CF₂— - . . . V . . . - —CH═CH— - . . . V .. . —CH═CH— - . . . Z . . . - —CO—O— - . . . Z . . . —CO—O— - . . . ZI .. . - —O—CO— - . . . ZI . . . —O—CO— - . . . K . . . - —CO— - . . . K .. . —CO— - . . . W . . . - —CF═CF— - . . . W . . . —CF═CF— in which nand m are each integers, and the three dots “. . .” are place-holdersfor other abbreviations from this table.

Besides the compounds of formula I, the mixtures according to theinvention preferably comprise one or more compounds of the compoundsmentioned below.

The following abbreviations are used:

(n, m and l are, independently of one another, each an integer,preferably 1 to 6, l possibly may also be 0 and preferably is 0 or 2)

TABLE D Exemplary, preferred compounds of formula I having a high ε_(⊥):

YG-n-F

YG-nO-F

YG-nO-OD

YG-n-OD

YG-n-T

YG-nO-T

YG-n-OT

YG-nO-OT

CK-n-F

B-n-m

B-n-Om

B-nO-Om

B-n-F

B-nO-F

B-n-T

B-nO-T

B-n-OT

B-nO-OT Exemplary, preferred dielectrically positive compounds

CP-n-F

CP-n-CL

GP-n-F

GP-n-CL

CCP-n-OT

CCG-n-OT

CCG-n-F

CCG-V-F

CCG-nV-F

CCU-n-F

CCEP-n-F

CCEU-n-F

CCEU-n-F

CDU-n-F

CPG-n-F

CPU-n-F

CPU-n-OXF

CGG-n-F

CGG-n-OD

CGU-n-F

PGU-n-F

GGP-n-F

GGP-n-CL

PGIGI-n-F

PGIGI-n-CL

CCPU-n-F

CCGU-n-F

CPGU-n-F

CPGU-n-OT

PPGU-n-F

DPGU-n-F

CCZU-n-F

PUZU-n-F

CCOC-n-m

CCQG-n-F

CCQU-n-F

PUQU-n-F

CDUQU-n-F

CPUQU-n-F

CGUQU-n-F

PGUQU-n-F

APUQU-n-F

DPUQU-n-F

DGUQU-n-F

CPU-n-F

DAUQU-n-F

CLUQU-n-F

ALUQU-n-F

DLUQU-n-F

LGPQU-n-F Exemplary, preferred dielectrically neutral compounds

CC-n-m

CC-n-Om

CC-n-V

CC-n-Vm

CC-n-mV

CC-n-mVI

CC-V-V

CC-V-mV

CC-V-Vm

CC-Vn-mV

CC-nV-mV

CC-nV-Vm

CC-n-VV

CC-n-VVm

CVC-n-V

CVC-n-Vm

CP-n-m

CP-n-Om

PP-n-m

PP-n-Om

CCP-n-m

CCP-n-Om

CCP-V-m

CCP-nV-m

CCP-Vn-m

CCP-nVm-I

CPP-n-m

CPG-n-m

CGP-n-m

PGP-n-m

PGP-n-mV

PGP-n-mVI

CCZPC-n-m

CPPC-n-m

CGPC-n-m

CPGP-n-m Exemplary, preferred dielectrically negative compounds

CY-V-n

CY-V-On

CY-nV-m

CY-nV-Om

CY-Vn-m

CY-Vn-Om

CY-nVm-I

CY-nVm-OI

PY-V-n

PY-V-On

PY-nV-m

PY-nV-Om

PY-Vn-m

PY-Vn-Om

PY-nVm-I

PY-nVm-OI

CCY-V-n

CCY-V-On

CCY-nV-m

CCY-nV-Om

CCY-Vn-m

CCY-Vn-Om

CCY-nVm-I

CCY-nVm-OI

CPY-V-n

CPY-V-On

CPY-nV-m

CPY-nV-Om

CPY-Vn-m

CPY-Vn-Om

CPY-nVm-I

CPY-nVm-OI

CY-n-m

CYn-Om

CVY-n-m

CVY-V-n

CZY-n-Om

COY-n-m

COY-n-Om

Y-n-m

Y-n-Om

Y-nO-Om

PY-n-m

PY-n-Om

CCY-n-m

CCY-n-Om

CCY-n-mOI

CCZY-n-Om

CCOY-n-m

CCOY-n-Om

CPY-n-m

CPY-n-Om

PYP-n-m

CP(F,Cl)-n-Om

CLY-n-m

CLY-n-Om

ACQU-n-F

Table E shows chiral dopants which are preferably employed in themixtures according to the invention.

TABLE E

C 15

CB 15

CM 21

R S-811/S-811

CM 44

CM 45

CM 47

CN

R-1011/S-1011

R-2011/S-2011

R-3011/S-3011

R-4011/S-4011

R-5011/S-5011

In a preferred embodiment of the present invention, the media accordingto the invention comprise one or more compounds selected from the groupof the compounds from Table E.

Table F shows stabilizers which can preferably be employed in themixtures according to the invention in addition to the compounds offormula I. The parameter n here denotes an integer in the range from 1to 12. In particular, the phenol derivatives shown can be employed asadditional stabilizers since they act as antioxidants.

TABLE F

In a preferred embodiment of the present invention, the media accordingto the invention comprise one or more compounds selected from the groupof the compounds from Table F, in particular one or more compoundsselected from the group of the compounds of the following two formulae

EXAMPLES

The following examples explain the present invention without restrictingit in any way. However, the physical properties make it clear to theperson skilled in the art what properties can be achieved and in whatranges they can be modified. In particular, the combination of thevarious properties which can preferably be achieved is thus well definedfor the person skilled in the art.

COMPOUND EXAMPLES

Exemplary compounds having a high dielectric constant perpendicular tothe director (ε_(⊥)) and a high average dielectric constant (ε_(av.))are exemplified in the following compound examples.

Compound Examples 1.1 and 1.2

Compounds of formula I-1 are e.g.

This compound (CK-3-F) has a melting point of 85° C., a Δε of −8.4 andan ε_(av.) of 13.4.

This compound (CK-5-F) has a phase sequence of K 74° C. N (63.7° C.) l,a Δε of −7.8 and an ε_(av.) of 12.2.

Compound Example 2

A compound of formula I-2 is e.g.

This compound (YG-2O-F) has a melting point of 69° C., a Δε of only +1.0and an ε_(av.) of already 13.4.

Compound Examples 3 and 4

Compounds of formula I-3 are e.g.

This compound (B-2O-O5) has a melting point of 57° C., a Δε of −13.7 andan ε_(av.) of even 17.9.

This compound (B-4O-O5) has similar preferably properties.

Compound Example 5

A compound of formula I-4 is e.g.

This compound (B-5O-OT) has a melting point of 64° C., a Δε of only −3.7and an ε_(av.) of even 18.6.

MIXTURE EXAMPLES

In the following are exemplary mixtures disclosed.

Example 1

The following mixture (M-1) is prepared and investigated.

Mixture 1 Composition Compound Concentration No. Abbreviation /% byweight 1 CY-3-O4 14.0 2 CK-3-F 6.0 3 CK-5-F 6.0 4 B-2O-O5 5.5 5 YG-2O-F5.0 6 CCY-3-O1 8.0 7 CCY-3-O2 12.0 8 CCY-3-O3 12.0 9 PUQU-3-F 11.0 10DGUQU-4-F 8.0 11 CDUQU-3-F 6.5 12 APUQU-3-F 6.0 Σ 100.0 Physicalproperties T(N, I) = 78.0° C. n_(e)(20° C., 589 nm) = 1.5927 Δn(20° C.,589 nm) = 0.1147 ε_(∥)(20°, 1 kHz) = 20.5 ε_(⊥)(20°, 1 kHz) = 14.0Δε(20°, 1 kHz) = 6.5 ε_(av.)(20°, 1 kHz) = 16.2 γ₁(20° C.) = 342 mPa · sk₁₁(20° C.) = 12.0 pN k₂₂(20° C.) = 6.5 pN k₃₃(20° C.) = 14.0 pN V₀(20°C.) = 1.42 V

This mixture, mixture M-1, has a dielectric ratio (ε_(⊥)/Δε) of 2.2 andis characterized by a very good transmission in an FFS display and showsa very short response time.

Example 2

The following mixture (M-2) is prepared and investigated.

Mixture 2 Composition Compound Concentration No. Abbreviation /% byweight 1 CY-3-O4 20.0 2 CK-4-F 6.0 3 CK-5-F 10.5 4 CCY-3-O1 8.0 5CCY-3-O2 12.0 6 CCY-3-O3 10.0 7 PUQU-3-F 12.0 8 DGUQU-4-F 8.0 9CDUQU-3-F 6.0 10 APUQU-3-F 7.5 Σ 100.0 Physical properties T(N, I) =79.0° C. n_(e)(20° C., 589 nm) = 1.5816 Δn(20° C., 589 nm) = 0.1058ε_(∥)(20°, 1 kHz) = 19.6 ε_(⊥)(20°, 1 kHz) = 12.3 Δε(20°, 1 kHz) = 7.2ε_(av.)(20°, 1 kHz) = 14.7 γ₁(20° C.) = 325 mPa · s k₁₁(20° C.) = 11.9pN k₂₂(20° C.) = t.b.d. pN k₃₃(20° C.) = 14.9 pN V₀(20° C.) = 1.35 VRemark: t.b.d.: to be determined.

This mixture, mixture M-2, has a dielectric ratio (ε_(⊥)/Δε) of 1.7 andis characterized by a good transmission in an FFS display and shows ashort response time.

Example 3

The following mixture (M-3) is prepared and investigated.

Mixture 3 Composition Compound Concentration No. Abbreviation /% byweight 1 CY-3-O2 8.0 2 CY-3-O4 15.0 3 CK-3-F 6.0 4 CCY-2-1 12.5 5CCY-3-O1 7.0 6 CCY-3-O2 12.0 7 CCY-3-O3 8.0 8 PUQU-3-F 12.0 9 DGUQU-4-F7.0 10 CDUQU-3-F 6.0 11 APUQU-3-F 6.5 Σ 100.0 Physical properties T(N,I) = 79.0° C. n_(e)(20° C., 589 nm) = 1.5838 Δn(20° C., 589 nm) = 0.1060ε_(∥)(20°, 1 kHz) = 17.3 ε_(⊥)(20°, 1 kHz) = 10.9 Δε(20°, 1 kHz) = 6.4ε_(av.)(20°, 1 kHz) = 13.0 γ₁(20° C.) = 297 mPa · s k₁₁(20° C.) = 11.9pN k₂₂(20° C.) = t.b.d. pN k₃₃(20° C.) = 15.3 pN V₀(20° C.) = 1.43 VRemark: t.b.d.: to be determined

This mixture, mixture M-3, has a dielectric ratio (ε_(⊥)/Δε) of 1.7 andis characterized by a good transmission in an FFS display and shows ashort response time.

Example 4

The following mixture (M-4) is prepared and investigated.

Mixture 4 Composition Compound Concentration No. Abbreviation /% byweight 1 CY-3-O4 15.0 2 YG-2O-F 6.0 3 ACQU-3-F 12.5 4 CCQU-3-F 8.0 5CLY-2-1 10.0 6 CCY-3-O2 10.0 7 CCOY-3-1 15.0 8 CGG-3-OD 15.0 9 DGUQU-2-F3.0 10 DGUQU-4-F 5.5 Σ 100.0 Physical properties T(N, I) = 80.0° C.n_(e)(20° C., 589 nm) = 1.5798 Δn(20° C., 589 nm) = 0.1036 ε_(∥)(20°, 1kHz) = 16.1 ε_(⊥)(20°, 1 kHz) = 9.7 Δε(20°, 1 kHz) = 6.5 ε_(av.)(20°, 1kHz) = 11.8 γ₁(20° C.) = 287 mPa · s k₁₁(20° C.) = 12.0 pN k₂₂(20° C.) =6.6 pN k₃₃(20° C.) = 15.0 pN V₀(20° C.) = 1.44 V

This mixture, mixture M-4, has a dielectric ratio (ε_(⊥)/Δε) of 1.5 andis characterized by a good transmission in an FFS display and shows ashort response time.

Example 5

The following mixture (M-5) is prepared and investigated.

Mixture 5 Composition Compound Concentration No. Abbreviation /% byweight 1 CGG-3-OD 21.0 2 PUQU-2-F 4.0 3 CCZU-2-F 4.0 4 CCZU-3-F 14.0 5APUQU-3-F 5.0 6 CC-3-V 4.0 7 YG-2O-F 5.0 8 CY-3-O4 6.0 9 CY-5-O2 10.0 10CCY-3-O2 9.0 11 CCY-5-O2 9.0 12 CZY-3-O2 9.0 Σ 100.0 Physical propertiesT(N, I) = 78.0° C. n_(e)(20° C., 589 nm) = 1.5818 Δn(20° C., 589 nm) =0.1045 ε_(∥)(20°, 1 kHz) = 14.6 ε_(⊥)(20°, 1 kHz) = 9.4 Δε(20°, 1 kHz) =5.2 ε_(av.)(20°, 1 kHz) = 11.2 γ₁(20° C.) = 211 mPa · s k₁₁(20° C.) =11.0 pN k₂₂(20° C.) = 6.7 pN k₃₃(20° C.) = 14.7 pN V₀(20° C.) = 1.52 V

This mixture, mixture M-5, has a dielectric ratio (ε_(⊥)/Δε) of 1.8 andis characterized by a good transmission in an FFS display and shows ashort response time.

Example 6

The following mixture (M-6) is prepared and investigated.

Mixture 6 Composition Compound Concentration No. Abbreviation /% byweight 1 CC-3-V 11.0 2 YG-2O-F 6.0 3 CY-3-O4 18.0 4 ACQU-3-F 6.5 5CCP-3-OT 5.5 6 CCP-3-1 5.0 7 CCY-3-O2 10.0 8 CCY-5-O2 10.0 9 CGG-3-OD15.0 10 APUQU-3-F 2.0 11 DGUQU-2-F 3.0 12 DGUQU-4-F 8.0 Σ 100.0 Physicalproperties T(N, I) = 79.5° C. n_(e)(20° C., 589 nm) = 1.5782 Δn(20° C.,589 nm) = 0.1016 ε_(∥)(20°, 1 kHz) = 14.5 ε_(⊥)(20°, 1 kHz) = 8.3Δε(20°, 1 kHz) = 6.2 ε_(av.)(20°, 1 kHz) = 10.4 γ₁(20° C.) = 180 mPa · sk₁₁(20° C.) = 11.9 pN k₂₂(20° C.) = 6.0 pN k₃₃(20° C.) = 14.1 pN V₀(20°C.) = 1.46 V

This mixture, mixture M-6, has a dielectric ratio (ε_(⊥)/Δε) of 1.3 andis characterized by a good transmission in an FFS display and shows ashort response time.

Example 7

The following mixture (M-7) is prepared and investigated.

Mixture 7 Composition Compound Concentration No. Abbreviation /% byweight 1 CC-3-V 17.0 2 YG-2O-F 6.0 3 CY-3-O4 18.0 4 CCP-3-OT 8.0 5CCP-3-1 2.0 6 CCY-3-O2 12.0 7 CCY-5-O2 8.0 8 CGG-3-OD 15.0 9 APUQU-3-F3.0 10 DGUQU-2-F 3.0 11 DGUQU-4-F 8.0 Σ 100.0 Physical properties T(N,I) = 75.5° C. n_(e)(20° C., 589 nm) = 1.5766 Δn(20° C., 589 nm) = 0.0997ε_(∥)(20°, 1 kHz) = 13.1 ε_(⊥)(20°, 1 kHz) = 8.0 Δε(20°, 1 kHz) = 5.2ε_(av.)(20°, 1 kHz) = 9.7 γ₁(20° C.) = 151 mPa · s k₁₁(20° C.) = 11.5 pNk₂₂(20° C.) = t.b.d. pN k₃₃(20° C.) = 13.7 pN V₀(20° C.) = 1.58 VRemark: t.b.d.: to be determined

This mixture, mixture M-7, has a dielectric ratio (ε_(⊥)/Δε) of 1.5 andis characterized by a good transmission in an FFS display and shows ashort response time.

Example 8

The following mixture (M-8) is prepared and investigated.

Mixture 8 Composition Compound Concentration No. Abbreviation /% byweight 1 CC-3-V 25.0 2 CY-3-O2 1.0 3 B-5O-OT 7.0 4 CCY-3-O1 11.0 5CCY-3-O2 13.0 6 CCY-3-O3 15.0 7 PUQU-3-F 10.0 8 CCQU-3-F 10.0 9CDUQU-3-F 8.0 Σ 100.0 Physical properties T(N, I) = 95° C. n_(e)(20° C.,589 nm) = 1.5679 Δn(20° C., 589 nm) = 0.0937 ε_(∥)(20°, 1 kHz) = 11.2ε_(⊥)(20°, 1 kHz) = 7.5 Δε(20°, 1 kHz) = 3.6 ε_(av.)(20°, 1 kHz) = 8.7γ₁(20° C.) = 161 mPa · s k₁₁(20° C.) = 14.7 pN k₂₂(20° C.) = 7.4 pNk₃₃(20° C.) = 16.6 pN V₀(20° C.) = 2.11 V

This mixture, mixture M-8, has a dielectric ratio (ε_(⊥)/Δε) of 2.1 andis characterized by a very good transmission in an FFS display and showsa very short response time.

Example 9

The following mixture (M-9) is prepared and investigated.

Mixture 9 Composition Compound Concentration No. Abbreviation /% byweight 1 CC-3-V 13.0 2 CCP-3-1 10.0 3 CK-3-F 6.0 4 CK-4-F 5.0 5 CK-5-F8.0 6 CCY-2-1 16.0 7 CCY-3-1 14.0 8 CGG-3-F 11.0 9 PUQU-3-F 6.0 10CDUQU-3-F 7.0 11 APUQU-3-F 4.0 Σ 100.0 Physical properties T(N, I) =90.5° C. n_(e)(20° C., 589 nm) = 1.5781 Δn(20° C., 589 nm) = 0.0972ε_(∥)(20°, 1 kHz) = 10.8 ε_(⊥)(20°, 1 kHz) = 7.2 Δε(20°, 1 kHz) = 3.6ε_(av.)(20°, 1 kHz) = 8.4 γ₁(20° C.) = 182 mPa · s k₁₁(20° C.) = 14.1 pNk₂₂(20° C.) = t.b.d. pN k₃₃(20° C.) = 17.0 pN V₀(20° C.) = 2.08 VRemark: t.b.d.: to be determined.

This mixture, mixture M-9, has a dielectric ratio (ε_(⊥)/Δε) of 2.0 andis characterized by a good transmission in an FFS display and shows avery short response time.

Example 10

The following mixture (M-10) is prepared and investigated.

Mixture 10 Composition Compound Concentration No. Abbreviation /% byweight 1 Y-3-O1 6.0 2 B-2O-O5 6.0 3 CC-3-V 10.5 4 YG-2O-F 6.0 5 CCP-3-OT6.5 6 CCP-V-1 17.0 7 CCP-V2-1 7.0 8 CGP-3-2 5.0 9 CGG-3-F 15.0 10CCY-3-O2 10.0 11 APUQU-3-F 3.0 12 DGUQU-4-F 8.0 Σ 100.0 Physicalproperties T(N, I) = 79° C. n_(e)(20° C., 589 nm) = 1.6005 Δn(20° C.,589 nm) = 0.1103 ε_(∥)(20°, 1 kHz) = 11.7 ε_(⊥)(20°, 1 kHz) = 7.0Δε(20°, 1 kHz) = 4.7 ε_(av.)(20°, 1 kHz) = 8.6 γ₁(20° C.) = 117 mPa · sk₁₁(20° C.) = 11.3 pN k₂₂(20° C.) = 6.5 pN k₃₃(20° C.) = 14.4 pN V₀(20°C.) = 1.61 V

This mixture, mixture M-10, has a dielectric ratio (ε_(⊥)/Δε) of 1.5 andis characterized by a good transmission in an FFS display and shows ashort response time.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The preceding preferred specific embodiments andexamples are, therefore, to be construed as merely illustrative, and notlimitative of the remainder of the disclosure in any way whatsoever.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

The entire disclosures of all applications, patents and publications,cited herein and of corresponding EP Application No. 15001057.7, filedApr. 13, 2015, and EP Application No. 15001531.1, filed May 21, 2015,are incorporated by reference herein.

The invention claimed is:
 1. A liquid-crystalline medium having anematic phase and a dielectric anisotropy (Δε) of 0.5 or more, saidmedium having (a) a dielectric constant perpendicular to the director(ε_(⊥)) in the range of 2 or more to 8 or less and at the same time aratio of the dielectric constant perpendicular to the director (ε_(⊥))to the dielectric anisotropy (Δε), (ε_(⊥)/Δε), of 1.0 or more, or (b) adielectric constant perpendicular to the director (ε_(⊥)) of 8 or moreand a dielectric anisotropy (Δε) of 26 or less; and wherein said mediumcomprises one or more compounds having a high dielectric constantperpendicular to the director (ε_(⊥)) and a high average dielectricconstant (ε_(av.)), which are compounds of formula I,

in which

denotes

denotes

n denotes 0 or 1, R¹¹ and R¹² independently of each other denote alkyl,alkoxy, fluorinated alkyl or fluorinated alkoxy, each having 1 to 7 Catoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2to 7 C atoms, and R¹¹ alternatively denotes R¹ and R¹² alternativelydenotes X¹, R¹ denotes alkyl, alkoxy, fluorinated alkyl or fluorinatedalkoxy having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl orfluorinated alkenyl having 2 to 7 C atoms, and X¹ denotes F, Cl,fluorinated alkyl, fluorinated alkenyl, fluorinated alkoxy orfluorinated alkenyloxy, the latter four groups having 1 to 4 C atoms. 2.The medium according to claim 1, wherein said medium has a dielectricconstant perpendicular to the director (ε_(⊥)) in the range of 2 or moreto less 8 or less and at the same time a ratio of the dielectricconstant perpendicular to the director (ε_(⊥)) to the dielectricanisotropy (Δε) of 1.0 or more.
 3. The medium according to claim 1,wherein said medium has a dielectric constant perpendicular to thedirector (ε_(⊥)) of 8 or more and a dielectric anisotropy (Δε) of 26 orless.
 4. The liquid-crystalline medium according to claim 3, whereinsaid medium has a ratio of the dielectric constant perpendicular to thedirector (ε_(⊥)) to the dielectric anisotropy (Δε) of 1.0 or more. 5.The liquid-crystalline medium according to claim 1, wherein said mediumhas a dielectric constant perpendicular to the director (ε_(⊥)) of 20 orless.
 6. The liquid-crystalline medium according to claim 5, whereinsaid medium comprises one or more compounds having a high dielectricconstant perpendicular to the director (ε_(⊥)) and a high averagedielectric constant (ε_(av.)).
 7. The medium according to claim 1,wherein the total concentration of the compounds of formula I in themedium as a whole is 1% or more to 60% or less.
 8. The medium accordingto claim 1, wherein said medium further comprises one or more chiralcompounds.
 9. An electro-optical display or electro-optical componentcomprising a liquid-crystalline medium according to claim
 1. 10. Thedisplay according to claim 9, wherein said display is based on the IPS-or FFS mode.
 11. The display according to claim 9, wherein said displaycontains an active-matrix addressing device.
 12. A method of generatingan electro-optical effect comprising applying voltage to a displayaccording to claim
 9. 13. The display according to claim 9, wherein saiddisplay is a mobile display.
 14. A process for the preparation of aliquid-crystalline medium according to claim 1, comprising mixing one ormore compounds of formula I with one or more additional mesogeniccompounds.
 15. The medium according to claim 1, wherein said medium hasan average dielectric constant (ε_(av.)≡(ε_(∥)+2ε_(⊥))/3) in the rangefrom 8.0 or more to 25.0 or less.
 16. The medium according to claim 15,wherein said medium has an average dielectric constant(ε_(av.)≡(ε_(∥)+2ε_(⊥))/3) in the range from 8.5 or more to 20.0 orless.
 17. The medium according to claim 15, wherein said medium has adielectric constant perpendicular to the director of the liquid crystalmolecules (ε_(⊥)) of 5.0 or more to 8 or less.
 18. The medium accordingto claim 1, wherein said medium further contains: one or moredielectrically positive compounds selected from the compounds offormulae II and III

in which R² denotes alkyl, alkoxy, fluorinated alkyl or fluorinatedalkoxy having 1 to 7 C atoms, or alkenyl, alkenyloxy, alkoxyalkyl orfluorinated alkenyl having 2 to 7 C atoms,

on each appearance, independently of one another, denote

L²¹ and L²² denote H or F, X² denotes halogen, halogenated alkyl oralkoxy having 1 to 3 C atoms or halogenated alkenyl or alkenyloxy having2 or 3 C atoms, m denotes 0, 1, 2 or 3, R³ denotes alkyl, alkoxy,fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms, oralkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 Catoms,

on each appearance, independently of one another, are

L³¹ and L³², independently of one another, denote H or F, X³ denoteshalogen, halogenated alkyl or alkoxy having 1 to 3 C atoms orhalogenated alkenyl or alkenyloxy having 2 or 3 C atoms, Z³ denotes—CH₂CH₂—, —CF₂CF₂—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH₂O— or asingle bond, and n denotes 0, 1, 2 or
 3. 19. The medium according toclaim 1, wherein said medium has a dielectric ratio (ε_(⊥)/Δε) of 1.5 ormore.
 20. The medium according to claim 18, wherein said medium has adielectric constant perpendicular to the director of the liquid crystalmolecules (ε_(⊥)) of 9 or more.
 21. The medium according to claim 18,wherein said medium further contains one or more dielectrically neutralcompounds selected from the compounds of formulae IV and V:

in which R⁴¹ and R⁴², independently of one another, denote alkyl,alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms,or alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7C atoms,

independently of one another and, if

occurs twice, also these independently of one another, denote

Z⁴¹ and Z⁴², independently of one another and, if Z⁴¹ occurs twice, alsothese independently of one another, denote —CH₂CH₂—, —COO—,trans-CH═CH—, trans-CF═CF—, —CH₂O—, —CF₂O—, —C≡C— or a single bond, pdenotes 0, 1 or 2, R⁵¹ and R⁵², independently of one another, denotealkyl having 1 to 7 C atoms, alkoxy having 1 to 7 C atoms, oralkoxyalkyl, alkenyl or alkenyloxy having 2 to 7 C atoms,

if present, each, independently of one another, denote

Z⁵¹ to Z⁵³ each, independently of one another, denote —CH₂—CH₂—,—CH₂—O—, —CH═CH—, —C≡C—, —COO— or a single bond, and i and j each,independently of one another, denote 0 or
 1. 22. The medium according toclaim 18, wherein said medium contains one or more dielectricallynegative compounds selected from the compounds of formulae VI to IX:

wherein R⁶¹ denotes an unsubstituted alkyl radical having 1 to 7 Catoms, an unsubstituted alkenyl radical having 2 to 7 C atoms, anunsubstituted alkoxy radical having 1 to 6 C atoms, or an unsubstitutedalkenyloxy radical having 2 to 6 C atoms, R⁶² denotes an unsubstitutedalkyl radical having 1 to 7 C atoms, an unsubstituted alkoxy radicalhaving 1 to 6 C atoms, or an unsubstituted alkenyloxy radical having 2to 6 C atoms, and l denotes 0 or 1, R⁷¹ denotes an unsubstituted alkylradical having 1 to 7 C atoms, or an unsubstituted alkenyl radicalhaving 2 to 7 C atoms, R⁷² denotes an unsubstituted alkyl radical having1 to 7 C atoms, an unsubstituted alkoxy radical having 1 to 6 C atoms,or an unsubstituted alkenyloxy radical having 2 to 6 C atoms, and

denotes

R⁸¹ denotes an unsubstituted alkyl radical having 1 to 7 C atoms, or anunsubstituted alkenyl radical having 2 to 7 C atoms, R⁸² denotes anunsubstituted alkyl radical having 1 to 7 C atoms, an unsubstitutedalkoxy radical having 1 to 6 C atoms, or an unsubstituted alkenyloxyradical having 2 to 6 C atoms,

denotes

Z⁸ denotes —(C═O)—O—, —CH₂—O—, —CF₂—O— or —CH₂—CH₂—, o denotes 0 or 1,R⁹¹ and R⁹² denotes an unsubstituted alkyl radical having 1 to 7 Catoms, an unsubstituted alkoxy radical having 1 to 6 C atoms, or anunsubstituted alkenyloxy radical having 2 to 6 C atoms,

denotes

p and q independently of each other denote 0 or
 1. 23. The mediumaccording to claim 1, wherein said one or more compounds of formula Iare selected from the compounds of formulae I-1 to I-4:

in which R¹¹ and R¹² independently of each other denote alkyl, alkoxy,fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms, oralkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 Catoms, R¹ denotes alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxyhaving 1 to 7 C atoms, or alkenyl, alkenyloxy, alkoxyalkyl orfluorinated alkenyl having 2 to 7 C atoms, and X¹ denotes F, Cl, CN,NCS, fluorinated alkyl having 1 to 4 C atoms, fluorinated alkenyl havingup to 4 C atoms, fluorinated alkoxy having 1 to 4 C atoms, orfluorinated alkenyloxy having up to 4 C atoms.